diff --git a/examples/example4.php b/examples/example4.php
new file mode 100644
index 00000000..692449af
--- /dev/null
+++ b/examples/example4.php
@@ -0,0 +1,77 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Example;
+
+use DateTimeImmutable;
+use Eluceo\iCal\Domain\Entity\Calendar;
+use Eluceo\iCal\Domain\Entity\Event;
+use Eluceo\iCal\Domain\Entity\RecurrenceRule;
+use Eluceo\iCal\Domain\Enum\RecurrenceFrequency;
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Day;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\SetPosition;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Count;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Exclusion;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Frequency;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Until;
+use Eluceo\iCal\Domain\ValueObject\TimeSpan;
+use Eluceo\iCal\Presentation\Factory\CalendarFactory;
+
+require_once __DIR__ . '/../vendor/autoload.php';
+
+// 1. Create the recurrence rule.
+$rrule = new RecurrenceRule();
+$rrule
+    ->setFrequency(new Frequency(RecurrenceFrequency::monthly()))
+    ->setCount(new Count(3))
+    ->setBy(new By([
+        new Day([
+            RecurrenceWeekDay::tuesday(),
+            RecurrenceWeekDay::wednesday(),
+            RecurrenceWeekDay::thursday()
+        ]),
+        new SetPosition([3])
+    ]))
+    ->setExclusions(new Exclusion([
+        new DateTime(new DateTimeImmutable('now'),true),
+        new DateTime(new DateTimeImmutable('2023-10-23T10:00:00'),true),
+    ]))
+    ->setUntil(new Until(new DateTime(new DateTimeImmutable('2023-12-31T10:00:00'),true)));
+
+// 2. Create Event domain entity.
+$event = new Event();
+$event
+    ->setSummary('Stand-up meeting')
+    ->setOccurrence(
+        new TimeSpan(
+            new DateTime(DateTimeImmutable::createFromFormat('Y-m-d H:i:s', '2023-10-15 10:00:00'), true),
+            new DateTime(DateTimeImmutable::createFromFormat('Y-m-d H:i:s', '2023-10-15 10:30:00'), true)
+        )
+    )
+    ->setRecurrenceRule($rrule)
+;
+
+// 3. Create Calendar domain entity.
+$calendar = new Calendar([$event]);
+
+// 4. Transform domain entity into an iCalendar component
+$componentFactory = new CalendarFactory();
+$calendarComponent = $componentFactory->createCalendar($calendar);
+
+// 5. Set HTTP headers.
+header('Content-Type: text/calendar; charset=utf-8');
+header('Content-Disposition: attachment; filename="cal.ics"');
+
+// 6. Output.
+echo $calendarComponent;
diff --git a/src/Domain/Entity/Event.php b/src/Domain/Entity/Event.php
index 641ec825..5c881132 100644
--- a/src/Domain/Entity/Event.php
+++ b/src/Domain/Entity/Event.php
@@ -34,6 +34,7 @@ class Event
     private ?Organizer $organizer = null;
     private ?Timestamp $lastModified = null;
     private ?EventStatus $status = null;
+    private ?RecurrenceRule $rrule = null;
 
     /**
      * @var array<Attendee>
@@ -347,4 +348,30 @@ public function unsetStatus(): self
 
         return $this;
     }
+
+    public function getRecurrenceRule(): RecurrenceRule
+    {
+        assert($this->rrule !== null);
+
+        return $this->rrule;
+    }
+
+    public function hasRecurrenceRule(): bool
+    {
+        return $this->rrule !== null;
+    }
+
+    public function setRecurrenceRule(RecurrenceRule $rrule): self
+    {
+        $this->rrule = $rrule;
+
+        return $this;
+    }
+
+    public function unsetRecurrenceRule(): self
+    {
+        $this->rrule = null;
+
+        return $this;
+    }
 }
diff --git a/src/Domain/Entity/RecurrenceRule.php b/src/Domain/Entity/RecurrenceRule.php
new file mode 100644
index 00000000..e52ec97d
--- /dev/null
+++ b/src/Domain/Entity/RecurrenceRule.php
@@ -0,0 +1,217 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\Entity;
+
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Count;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Exclusion;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Frequency;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Interval;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Until;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\WeekStart;
+use Eluceo\iCal\Presentation\Component\Property\Value\DateTimeValue;
+
+class RecurrenceRule
+{
+    private ?Until $until = null;
+    private ?Frequency $frequency = null;
+    private ?Count $count = null;
+    private ?Interval $interval = null;
+    private ?WeekStart $weekStart = null;
+    private ?By $by = null;
+    private ?Exclusion $exclusions = null;
+
+    public function getUntil(): ?Until
+    {
+        return $this->until;
+    }
+
+    public function hasUntil(): bool
+    {
+        return $this->until !== null;
+    }
+
+    public function setUntil(?Until $until): self
+    {
+        $this->until = $until;
+        return $this;
+    }
+
+    public function unsetUntil(): self
+    {
+        $this->until = null;
+        return $this;
+    }
+
+    public function getFrequency(): ?Frequency
+    {
+        return $this->frequency;
+    }
+
+    public function hasFrequency(): bool
+    {
+        return $this->frequency !== null;
+    }
+
+    public function setFrequency(?Frequency $frequency): self
+    {
+        $this->frequency = $frequency;
+        return $this;
+    }
+
+    public function unsetFrequency(): self
+    {
+        $this->frequency = null;
+        return $this;
+    }
+
+    public function getCount(): ?Count
+    {
+        return $this->count;
+    }
+
+    public function hasCount(): bool
+    {
+        return $this->count !== null;
+    }
+
+    public function setCount(?Count $count): self
+    {
+        $this->count = $count;
+        return $this;
+    }
+
+    public function unsetCount(): self
+    {
+        $this->count = null;
+        return $this;
+    }
+
+    public function getInterval(): ?Interval
+    {
+        return $this->interval;
+    }
+
+    public function hasInterval(): bool
+    {
+        return $this->interval !== null;
+    }
+
+    public function setInterval(?Interval $interval): self
+    {
+        $this->interval = $interval;
+        return $this;
+    }
+
+    public function unsetInterval(): self
+    {
+        $this->interval = null;
+        return $this;
+    }
+
+    public function getWeekStart(): ?WeekStart
+    {
+        return $this->weekStart;
+    }
+
+    public function hasWeekStart(): bool
+    {
+        return $this->weekStart !== null;
+    }
+
+    public function setWeekStart(?WeekStart $weekStart): self
+    {
+        $this->weekStart = $weekStart;
+        return $this;
+    }
+
+    public function unsetWeekStart(): self
+    {
+        $this->weekStart = null;
+        return $this;
+    }
+
+    public function getBy(): ?By
+    {
+        return $this->by;
+    }
+
+    public function hasBy(): bool
+    {
+        return !empty($this->by);
+    }
+
+    public function setBy(By $by): self
+    {
+        $this->by = $by;
+        return $this;
+    }
+
+    public function unsetBy(): self
+    {
+        $this->by = null;
+        return $this;
+    }
+
+    public function getExclusions(): ?Exclusion
+    {
+        return $this->exclusions;
+    }
+
+    public function hasExclusions(): bool
+    {
+        return !empty($this->exclusions);
+    }
+
+    public function setExclusions(Exclusion $exclusions): self
+    {
+        $this->exclusions = $exclusions;
+        return $this;
+    }
+
+    public function unsetExclusions(): self
+    {
+        $this->exclusions = null;
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        if (
+            !$this->hasUntil()
+            && !$this->hasFrequency()
+            && !$this->hasCount()
+            && !$this->hasInterval()
+            && !$this->hasInterval()
+            && !$this->hasWeekStart()
+            && !$this->hasBy()
+        ) {
+            return '';
+        }
+
+        $parts = [
+            $this->getUntil(),
+            $this->getFrequency(),
+            $this->getCount(),
+            $this->getInterval(),
+            $this->getWeekStart(),
+            $this->getBy()
+        ];
+
+        return implode(';', array_map('strval',
+            array_filter($parts, static function ($part) {
+                return !empty($part);
+            })
+        ));
+    }
+}
diff --git a/src/Domain/Enum/RecurrenceEnum.php b/src/Domain/Enum/RecurrenceEnum.php
new file mode 100644
index 00000000..51f60222
--- /dev/null
+++ b/src/Domain/Enum/RecurrenceEnum.php
@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\Enum;
+
+use InvalidArgumentException;
+use ReflectionClass;
+
+abstract class RecurrenceEnum
+{
+    protected string $value;
+
+    public function __construct(string $value)
+    {
+        $constants = (new ReflectionClass(static::class))->getConstants();
+        if (!in_array($value, $constants, true)) {
+            $allowedValues = implode(', ', $constants);
+            throw new InvalidArgumentException(
+                "Value must be one of: {$allowedValues}"
+            );
+        }
+        $this->value = $value;
+    }
+
+    public function __toString(): string
+    {
+        return strtoupper($this->value);
+    }
+}
diff --git a/src/Domain/Enum/RecurrenceFrequency.php b/src/Domain/Enum/RecurrenceFrequency.php
new file mode 100644
index 00000000..44af9692
--- /dev/null
+++ b/src/Domain/Enum/RecurrenceFrequency.php
@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\Enum;
+
+final class RecurrenceFrequency extends RecurrenceEnum
+{
+    public const SECONDLY = 'secondly';
+    public const MINUTELY = 'minutely';
+    public const HOURLY = 'hourly';
+    public const DAILY = 'daily';
+    public const WEEKLY = 'weekly';
+    public const MONTHLY = 'monthly';
+    public const YEARLY = 'yearly';
+
+    public static function secondly(): self
+    {
+        return new self(self::SECONDLY);
+    }
+
+    public static function minutely(): self
+    {
+        return new self(self::MINUTELY);
+    }
+
+    public static function hourly(): self
+    {
+        return new self(self::HOURLY);
+    }
+
+    public static function daily(): self
+    {
+        return new self(self::DAILY);
+    }
+
+    public static function weekly(): self
+    {
+        return new self(self::WEEKLY);
+    }
+
+    public static function monthly(): self
+    {
+        return new self(self::MONTHLY);
+    }
+
+    public function yearly(): self
+    {
+        return new self(self::YEARLY);
+    }
+}
diff --git a/src/Domain/Enum/RecurrenceWeekDay.php b/src/Domain/Enum/RecurrenceWeekDay.php
new file mode 100644
index 00000000..fc73b685
--- /dev/null
+++ b/src/Domain/Enum/RecurrenceWeekDay.php
@@ -0,0 +1,77 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\Enum;
+
+final class RecurrenceWeekDay extends RecurrenceEnum
+{
+    public const SUNDAY = 'SU';
+    public const MONDAY = 'MO';
+    public const TUESDAY = 'TU';
+    public const WEDNESDAY = 'WE';
+    public const THURSDAY = 'TH';
+    public const FRIDAY = 'FR';
+    public const SATURDAY = 'SA';
+
+    protected ?int $offset = null;
+
+
+    public function __construct(string $value, ?int $offset = null)
+    {
+        parent::__construct($value);
+        if ($offset !== null) {
+            if ($offset < -53 || $offset > 53) {
+                throw new \InvalidArgumentException('Day offsets must be between -53 and 53');
+            }
+            $this->offset = $offset;
+        }
+    }
+
+    public static function sunday(?int $offset = null): self
+    {
+        return new self(self::SUNDAY, $offset);
+    }
+
+    public static function monday(?int $offset = null): self
+    {
+        return new self(self::MONDAY, $offset);
+    }
+
+    public static function tuesday(?int $offset = null): self
+    {
+        return new self(self::TUESDAY, $offset);
+    }
+
+    public static function wednesday(?int $offset = null): self
+    {
+        return new self(self::WEDNESDAY, $offset);
+    }
+
+    public static function thursday(?int $offset = null): self
+    {
+        return new self(self::THURSDAY, $offset);
+    }
+
+    public static function friday(?int $offset = null): self
+    {
+        return new self(self::FRIDAY, $offset);
+    }
+
+    public static function saturday(?int $offset = null): self
+    {
+        return new self(self::SATURDAY, $offset);
+    }
+
+    public function __toString(): string
+    {
+        return ($this->offset !== null ? (string)$this->offset : '') . parent::__toString();
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By.php b/src/Domain/ValueObject/Recurrence/By.php
new file mode 100644
index 00000000..40ed8528
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By.php
@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use InvalidArgumentException;
+use TypeError;
+
+final class By
+{
+    /** @var array<By\Second|By\Minute|By\Hour|By\Day|By\MonthDay|By\Month|By\YearDay|By\SetPosition|By\WeekNumber> */
+    private array $by;
+
+    public function __construct(array $by)
+    {
+        foreach ($by as $checkBy) {
+            try {
+                if (!in_array(get_class($checkBy), [
+                    By\Second::class,
+                    By\Minute::class,
+                    By\Hour::class,
+                    By\Day::class,
+                    By\MonthDay::class,
+                    By\Month::class,
+                    By\YearDay::class,
+                    By\SetPosition::class,
+                    By\WeekNumber::class
+                ])) {
+                    $this->throwInvalid();
+                }
+            } catch (TypeError $e) {
+                $this->throwInvalid();
+            }
+        }
+
+        $this->by = $by;
+    }
+
+    private function throwInvalid(): void
+    {
+        throw new InvalidArgumentException('Values must be one of: Day, Hour, Minute, Month, MonthDay, Second, SetPosition, WeekNumber, YearDay');
+    }
+
+    public function __toString(): string
+    {
+        return implode(';', array_map(static function ($by) {
+            return (string)$by;
+        }, $this->by));
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/Day.php b/src/Domain/ValueObject/Recurrence/By/Day.php
new file mode 100644
index 00000000..145528a5
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/Day.php
@@ -0,0 +1,46 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+
+class Day
+{
+    private array $days;
+
+    /**
+     * Accepts one or more recurrence days
+     *
+     * For example:
+     *
+     *   [RecurrenceWeekDay::monday(), RecurrenceWeekDay::sunday(-3)]
+     *
+     * If the offset is given, it must be between -53 and 53.
+     *
+     * @param array<RecurrenceWeekDay> $days
+     */
+    public function __construct(array $days)
+    {
+        foreach ($days as $day) {
+            if (!is_a($day, RecurrenceWeekDay::class)) {
+                throw new \InvalidArgumentException('Day must be an instance of RecurrenceWeekDay');
+            }
+        }
+
+        $this->days = $days;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYDAY=' . implode(',', $this->days);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/Hour.php b/src/Domain/ValueObject/Recurrence/By/Hour.php
new file mode 100644
index 00000000..b987d044
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/Hour.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class Hour
+{
+    /** @var array<int> */
+    private array $hours;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $hour) {
+            if ($hour < 0 || $hour > 23) {
+                throw new InvalidArgumentException('Hour values must be between 0 and 23');
+            }
+        }
+
+        $this->hours = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYHOUR=' . implode(',', $this->hours);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/Minute.php b/src/Domain/ValueObject/Recurrence/By/Minute.php
new file mode 100644
index 00000000..8c0f9f0f
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/Minute.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class Minute
+{
+    /** @var array<int> */
+    private array $minutes;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $minute) {
+            if ($minute < 0 || $minute > 59) {
+                throw new InvalidArgumentException('Minute values must be between 0 and 59');
+            }
+        }
+
+        $this->minutes = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYMINUTE=' . implode(',', $this->minutes);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/Month.php b/src/Domain/ValueObject/Recurrence/By/Month.php
new file mode 100644
index 00000000..79447e7d
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/Month.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class Month
+{
+    /** @var array<int> */
+    private array $months;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $month) {
+            if ($month < 1 || $month > 12) {
+                throw new InvalidArgumentException('Month values must be between 1 and 12');
+            }
+        }
+
+        $this->months = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYMONTH=' . implode(',', $this->months);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/MonthDay.php b/src/Domain/ValueObject/Recurrence/By/MonthDay.php
new file mode 100644
index 00000000..21b82204
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/MonthDay.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class MonthDay
+{
+    /** @var array<int> */
+    private array $monthDays;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $monthDay) {
+            if ($monthDay < -31 || $monthDay > 31 || $monthDay === 0) {
+                throw new InvalidArgumentException('Month day values must be between 1 and 31, or -1 and -31');
+            }
+        }
+
+        $this->monthDays = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYMONTHDAY=' . implode(',', $this->monthDays);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/Second.php b/src/Domain/ValueObject/Recurrence/By/Second.php
new file mode 100644
index 00000000..de0f5d6e
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/Second.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class Second
+{
+    /** @var array<int> */
+    private array $seconds;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $second) {
+            if ($second < 0 || $second > 60) {
+                throw new InvalidArgumentException('Second values must be between 0 and 60');
+            }
+        }
+
+        $this->seconds = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYSECONDS=' . implode(',', $this->seconds);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/SetPosition.php b/src/Domain/ValueObject/Recurrence/By/SetPosition.php
new file mode 100644
index 00000000..5172cebb
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/SetPosition.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class SetPosition
+{
+    /** @var array<int> */
+    private array $positions;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $position) {
+            if ($position < -366 || $position > 366 || $position === 0) {
+                throw new InvalidArgumentException('Position values must be between 1 and 366, or -1 and -366');
+            }
+        }
+
+        $this->positions = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYSETPOS=' . implode(',', $this->positions);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/WeekNumber.php b/src/Domain/ValueObject/Recurrence/By/WeekNumber.php
new file mode 100644
index 00000000..888de4af
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/WeekNumber.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class WeekNumber
+{
+    /** @var array<int> */
+    private array $weekNumbers;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $weekNumber) {
+            if ($weekNumber < -53 || $weekNumber > 53 || $weekNumber === 0) {
+                throw new InvalidArgumentException('Week number values must be between 1 and 53, or -1 and -53');
+            }
+        }
+
+        $this->weekNumbers = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYWEEKNO=' . implode(',', $this->weekNumbers);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/By/YearDay.php b/src/Domain/ValueObject/Recurrence/By/YearDay.php
new file mode 100644
index 00000000..cdb583b8
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/By/YearDay.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+
+use InvalidArgumentException;
+
+final class YearDay
+{
+    /** @var array<int> */
+    private array $yearDays;
+
+    public function __construct(array $value)
+    {
+        $value = array_map('intval', $value);
+
+        foreach ($value as $yearDay) {
+            if ($yearDay < -366 || $yearDay > 366 || $yearDay === 0) {
+                throw new InvalidArgumentException('Year day values must be between 1 and 366, or -1 and -366');
+            }
+        }
+
+        $this->yearDays = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'BYYEARDAY=' . implode(',', $this->yearDays);
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/Count.php b/src/Domain/ValueObject/Recurrence/Count.php
new file mode 100644
index 00000000..636b6f15
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/Count.php
@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use InvalidArgumentException;
+
+final class Count
+{
+    private int $count;
+
+    public function __construct(int $count)
+    {
+        if ($count < 1) {
+            throw new InvalidArgumentException('Count must be greater than 0');
+        }
+
+        $this->count = $count;
+    }
+
+    public function __toString(): string
+    {
+        return "COUNT={$this->count}";
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/Exclusion.php b/src/Domain/ValueObject/Recurrence/Exclusion.php
new file mode 100644
index 00000000..c04fdd64
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/Exclusion.php
@@ -0,0 +1,39 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use Eluceo\iCal\Presentation\Component\Property\Value\DateTimeValue;
+use InvalidArgumentException;
+
+class Exclusion
+{
+    /** @var array<DateTime> */
+    private array $exclusions;
+
+    public function __construct(array $value)
+    {
+        foreach ($value as $exclusion) {
+            if (!$exclusion instanceof DateTime) {
+                throw new InvalidArgumentException('Values must be DateTime objects');
+            }
+        }
+        $this->exclusions = $value;
+    }
+
+    public function __toString(): string
+    {
+        return implode(',', array_map(static function ($ex) {
+            return (string)(new DateTimeValue($ex));
+        }, $this->exclusions));
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/Frequency.php b/src/Domain/ValueObject/Recurrence/Frequency.php
new file mode 100644
index 00000000..4add587a
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/Frequency.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use Eluceo\iCal\Domain\Enum\RecurrenceFrequency;
+
+final class Frequency
+{
+    private RecurrenceFrequency $frequency;
+
+    public function __construct(RecurrenceFrequency $frequency)
+    {
+        $this->frequency = $frequency;
+    }
+
+    public function __toString(): string
+    {
+        return "FREQ={$this->frequency}";
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/Interval.php b/src/Domain/ValueObject/Recurrence/Interval.php
new file mode 100644
index 00000000..f99a81e5
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/Interval.php
@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use InvalidArgumentException;
+
+final class Interval
+{
+    private int $interval;
+
+    public function __construct(int $interval)
+    {
+        if ($interval < 1) {
+            throw new InvalidArgumentException('Interval must be greater than 0');
+        }
+
+        $this->interval = $interval;
+    }
+
+    public function __toString(): string
+    {
+        return "INTERVAL={$this->interval}";
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/Until.php b/src/Domain/ValueObject/Recurrence/Until.php
new file mode 100644
index 00000000..475af6b8
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/Until.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use Eluceo\iCal\Presentation\Component\Property\Value\DateTimeValue;
+
+class Until
+{
+    private DateTime $exclusions;
+
+    public function __construct(DateTime $value)
+    {
+        $this->exclusions = $value;
+    }
+
+    public function __toString(): string
+    {
+        return 'UNTIL=' . (new DateTimeValue($this->exclusions));
+    }
+}
diff --git a/src/Domain/ValueObject/Recurrence/WeekStart.php b/src/Domain/ValueObject/Recurrence/WeekStart.php
new file mode 100644
index 00000000..4584cad3
--- /dev/null
+++ b/src/Domain/ValueObject/Recurrence/WeekStart.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Domain\ValueObject\Recurrence;
+
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+
+final class WeekStart
+{
+    private RecurrenceWeekDay $weekStart;
+
+    public function __construct(RecurrenceWeekDay $weekStart)
+    {
+        $this->weekStart = $weekStart;
+    }
+
+    public function __toString(): string
+    {
+        return "WKST={$this->weekStart}";
+    }
+}
diff --git a/src/Presentation/Component/Property/Value/RawTextValue.php b/src/Presentation/Component/Property/Value/RawTextValue.php
new file mode 100644
index 00000000..25499aa7
--- /dev/null
+++ b/src/Presentation/Component/Property/Value/RawTextValue.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Presentation\Component\Property\Value;
+
+use Eluceo\iCal\Domain\ValueObject\Uri;
+use Eluceo\iCal\Presentation\Component\Property\Value;
+
+class RawTextValue extends Value
+{
+    private string $value;
+
+    public function __construct(string $value)
+    {
+        $this->value = $value;
+    }
+
+    public function __toString(): string
+    {
+        return $this->value;
+    }
+}
diff --git a/src/Presentation/Factory/EventFactory.php b/src/Presentation/Factory/EventFactory.php
index 88c8794f..e32b3c83 100644
--- a/src/Presentation/Factory/EventFactory.php
+++ b/src/Presentation/Factory/EventFactory.php
@@ -32,6 +32,7 @@
 use Eluceo\iCal\Presentation\Component\Property\Value\GeoValue;
 use Eluceo\iCal\Presentation\Component\Property\Value\IntegerValue;
 use Eluceo\iCal\Presentation\Component\Property\Value\ListValue;
+use Eluceo\iCal\Presentation\Component\Property\Value\RawTextValue;
 use Eluceo\iCal\Presentation\Component\Property\Value\TextValue;
 use Eluceo\iCal\Presentation\Component\Property\Value\UriValue;
 use Generator;
@@ -127,6 +128,13 @@ protected function getProperties(Event $event): Generator
         foreach ($event->getAttachments() as $attachment) {
             yield from $this->getAttachmentProperties($attachment);
         }
+
+        if ($event->hasRecurrenceRule()) {
+            yield new Property('RRULE', new RawTextValue((string)$event->getRecurrenceRule()));
+            if ($event->getRecurrenceRule()->hasExclusions()) {
+                yield new Property('EXDATE', new RawTextValue((string)$event->getRecurrenceRule()->getExclusions()));
+            }
+        }
     }
 
     /**
diff --git a/tests/Unit/Domain/Entity/RecurrenceRuleTest.php b/tests/Unit/Domain/Entity/RecurrenceRuleTest.php
new file mode 100644
index 00000000..e56db14c
--- /dev/null
+++ b/tests/Unit/Domain/Entity/RecurrenceRuleTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\Entity;
+
+use DateTime as PhpDateTime;
+use Eluceo\iCal\Domain\Enum\RecurrenceFrequency;
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Day;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Until;
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\Entity\RecurrenceRule;
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Count;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Exclusion;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Frequency;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Interval;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\WeekStart;
+
+class RecurrenceRuleTest extends TestCase
+{
+    public function testToStringWithAllPropertiesSet(): void
+    {
+        $recurrenceRule = (new RecurrenceRule())
+            ->setUntil(new Until(new DateTime(new PhpDateTime('2023-12-31T12:00:00'), true)))
+            ->setFrequency(new Frequency(RecurrenceFrequency::daily()))
+            ->setCount(new Count(5))
+            ->setInterval(new Interval(2))
+            ->setWeekStart(new WeekStart(RecurrenceWeekDay::monday()))
+            ->setBy(new By([new Day([RecurrenceWeekDay::thursday(-1)])]))
+            ->setExclusions(new Exclusion([new DateTime(new PhpDateTime('2023-12-31T12:00:00'), true)]));
+
+        $expected = 'UNTIL=20231231T120000;FREQ=DAILY;COUNT=5;INTERVAL=2;WKST=MO;BYDAY=-1TH';
+        $this->assertSame($expected, $recurrenceRule->__toString());
+    }
+
+    public function testToStringWithNoPropertiesSet(): void
+    {
+        $recurrenceRule = new RecurrenceRule();
+        $this->assertSame('', $recurrenceRule->__toString());
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/DayTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/DayTest.php
new file mode 100644
index 00000000..49d3fb8e
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/DayTest.php
@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Day;
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+
+class DayTest extends TestCase
+{
+    public function testConstructorWithSingleDay(): void
+    {
+        $day = new Day([RecurrenceWeekDay::monday()]);
+
+        $this->assertInstanceOf(Day::class, $day);
+        $this->assertSame('BYDAY=MO', $day->__toString());
+    }
+
+    public function testConstructorWithMultipleDays(): void
+    {
+        $days = new Day([RecurrenceWeekDay::monday(), RecurrenceWeekDay::sunday()]);
+
+        $this->assertInstanceOf(Day::class, $days);
+        $this->assertSame('BYDAY=MO,SU', $days->__toString());
+    }
+
+    public function testConstructorWithDayOffsets(): void
+    {
+        $days = new Day([
+            RecurrenceWeekDay::monday(5),
+            RecurrenceWeekDay::sunday(-3),
+        ]);
+
+        $this->assertInstanceOf(Day::class, $days);
+        $this->assertSame('BYDAY=5MO,-3SU', $days->__toString());
+    }
+
+    public function testConstructorWithInvalidOffsetValue(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Day offsets must be between -53 and 53');
+
+        new Day([RecurrenceWeekDay::monday(-54)]);
+    }
+
+    public function testConstructorWithInvalidDayType(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Day must be an instance of RecurrenceWeekDay');
+
+        new Day(['InvalidDay']);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/HourTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/HourTest.php
new file mode 100644
index 00000000..aa91455d
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/HourTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Hour;
+use InvalidArgumentException;
+
+class HourTest extends TestCase
+{
+    public function testConstructorWithSingleHour(): void
+    {
+        $hour = new Hour([8]);
+
+        $this->assertInstanceOf(Hour::class, $hour);
+        $this->assertSame('BYHOUR=8', $hour->__toString());
+    }
+
+    public function testConstructorWithMultipleHours(): void
+    {
+        $hours = new Hour([8, 16, 12]);
+
+        $this->assertInstanceOf(Hour::class, $hours);
+        $this->assertSame('BYHOUR=8,16,12', $hours->__toString());
+    }
+
+    public function testConstructorWithInvalidHourValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Hour values must be between 0 and 23');
+
+        new Hour([25]);
+    }
+
+    public function testConstructorWithInvalidHourArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Hour values must be between 0 and 23');
+
+        new Hour([8, 25, 16]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/MinuteTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/MinuteTest.php
new file mode 100644
index 00000000..332c16e2
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/MinuteTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Minute;
+use InvalidArgumentException;
+
+class MinuteTest extends TestCase
+{
+    public function testConstructorWithSingleMinute(): void
+    {
+        $minute = new Minute([15]);
+
+        $this->assertInstanceOf(Minute::class, $minute);
+        $this->assertSame('BYMINUTE=15', $minute->__toString());
+    }
+
+    public function testConstructorWithMultipleMinutes(): void
+    {
+        $minutes = new Minute([15, 30, 45]);
+
+        $this->assertInstanceOf(Minute::class, $minutes);
+        $this->assertSame('BYMINUTE=15,30,45', $minutes->__toString());
+    }
+
+    public function testConstructorWithInvalidMinuteValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Minute values must be between 0 and 59');
+
+        new Minute([60]);
+    }
+
+    public function testConstructorWithInvalidMinuteArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Minute values must be between 0 and 59');
+
+        new Minute([15, 60, 45]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/MonthDayTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/MonthDayTest.php
new file mode 100644
index 00000000..50f547f1
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/MonthDayTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\MonthDay;
+use InvalidArgumentException;
+
+class MonthDayTest extends TestCase
+{
+    public function testConstructorWithSingleMonthDay(): void
+    {
+        $monthDay = new MonthDay([15]);
+
+        $this->assertInstanceOf(MonthDay::class, $monthDay);
+        $this->assertSame('BYMONTHDAY=15', $monthDay->__toString());
+    }
+
+    public function testConstructorWithMultipleMonthDays(): void
+    {
+        $monthDays = new MonthDay([15, -1, -31]);
+
+        $this->assertInstanceOf(MonthDay::class, $monthDays);
+        $this->assertSame('BYMONTHDAY=15,-1,-31', $monthDays->__toString());
+    }
+
+    public function testConstructorWithInvalidMonthDayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Month day values must be between 1 and 31, or -1 and -31');
+
+        new MonthDay([0]);
+    }
+
+    public function testConstructorWithInvalidMonthDayArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Month day values must be between 1 and 31, or -1 and -31');
+
+        new MonthDay([15, 32, -33]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/MonthTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/MonthTest.php
new file mode 100644
index 00000000..2f8e939d
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/MonthTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Month;
+use InvalidArgumentException;
+
+class MonthTest extends TestCase
+{
+    public function testConstructorWithSingleMonth(): void
+    {
+        $month = new Month([5]);
+
+        $this->assertInstanceOf(Month::class, $month);
+        $this->assertSame('BYMONTH=5', $month->__toString());
+    }
+
+    public function testConstructorWithMultipleMonths(): void
+    {
+        $months = new Month([5, 8, 12]);
+
+        $this->assertInstanceOf(Month::class, $months);
+        $this->assertSame('BYMONTH=5,8,12', $months->__toString());
+    }
+
+    public function testConstructorWithInvalidMonthValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Month values must be between 1 and 12');
+
+        new Month([0]);
+    }
+
+    public function testConstructorWithInvalidMonthArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Month values must be between 1 and 12');
+
+        new Month([5, 0, 12]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/SecondTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/SecondTest.php
new file mode 100644
index 00000000..85e6aa3d
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/SecondTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Second;
+use InvalidArgumentException;
+
+class SecondTest extends TestCase
+{
+    public function testConstructorWithSingleSecond(): void
+    {
+        $second = new Second([30]);
+
+        $this->assertInstanceOf(Second::class, $second);
+        $this->assertSame('BYSECONDS=30', $second->__toString());
+    }
+
+    public function testConstructorWithMultipleSeconds(): void
+    {
+        $seconds = new Second([15, 30, 45]);
+
+        $this->assertInstanceOf(Second::class, $seconds);
+        $this->assertSame('BYSECONDS=15,30,45', $seconds->__toString());
+    }
+
+    public function testConstructorWithInvalidSecondValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Second values must be between 0 and 60');
+
+        new Second([61]);
+    }
+
+    public function testConstructorWithInvalidSecondArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Second values must be between 0 and 60');
+
+        new Second([15, 61, 45]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/SetPositionTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/SetPositionTest.php
new file mode 100644
index 00000000..06ea4f57
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/SetPositionTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\SetPosition;
+use InvalidArgumentException;
+
+class SetPositionTest extends TestCase
+{
+    public function testConstructorWithSinglePosition(): void
+    {
+        $position = new SetPosition([15]);
+
+        $this->assertInstanceOf(SetPosition::class, $position);
+        $this->assertSame('BYSETPOS=15', $position->__toString());
+    }
+
+    public function testConstructorWithMultiplePositions(): void
+    {
+        $positions = new SetPosition([15, -1, -366]);
+
+        $this->assertInstanceOf(SetPosition::class, $positions);
+        $this->assertSame('BYSETPOS=15,-1,-366', $positions->__toString());
+    }
+
+    public function testConstructorWithInvalidPositionValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Position values must be between 1 and 366, or -1 and -366');
+
+        new SetPosition([0]);
+    }
+
+    public function testConstructorWithInvalidPositionArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Position values must be between 1 and 366, or -1 and -366');
+
+        new SetPosition([15, 367, -367]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/WeekNumberTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/WeekNumberTest.php
new file mode 100644
index 00000000..2916b4e1
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/WeekNumberTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\WeekNumber;
+use InvalidArgumentException;
+
+class WeekNumberTest extends TestCase
+{
+    public function testConstructorWithSingleWeekNumber(): void
+    {
+        $weekNumber = new WeekNumber([15]);
+
+        $this->assertInstanceOf(WeekNumber::class, $weekNumber);
+        $this->assertSame('BYWEEKNO=15', $weekNumber->__toString());
+    }
+
+    public function testConstructorWithMultipleWeekNumbers(): void
+    {
+        $weekNumbers = new WeekNumber([15, -1, -53]);
+
+        $this->assertInstanceOf(WeekNumber::class, $weekNumbers);
+        $this->assertSame('BYWEEKNO=15,-1,-53', $weekNumbers->__toString());
+    }
+
+    public function testConstructorWithInvalidWeekNumberValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Week number values must be between 1 and 53, or -1 and -53');
+
+        new WeekNumber([0]);
+    }
+
+    public function testConstructorWithInvalidWeekNumberArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Week number values must be between 1 and 53, or -1 and -53');
+
+        new WeekNumber([15, 54, -54]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/By/YearDayTest.php b/tests/Unit/Domain/ValueObject/Recurrence/By/YearDayTest.php
new file mode 100644
index 00000000..402608c6
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/By/YearDayTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence\By;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\YearDay;
+use InvalidArgumentException;
+
+class YearDayTest extends TestCase
+{
+    public function testConstructorWithSingleYearDay(): void
+    {
+        $yearDay = new YearDay([100]);
+
+        $this->assertInstanceOf(YearDay::class, $yearDay);
+        $this->assertSame('BYYEARDAY=100', $yearDay->__toString());
+    }
+
+    public function testConstructorWithMultipleYearDays(): void
+    {
+        $yearDays = new YearDay([100, -1, -366]);
+
+        $this->assertInstanceOf(YearDay::class, $yearDays);
+        $this->assertSame('BYYEARDAY=100,-1,-366', $yearDays->__toString());
+    }
+
+    public function testConstructorWithInvalidYearDayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Year day values must be between 1 and 366, or -1 and -366');
+
+        new YearDay([0]);
+    }
+
+    public function testConstructorWithInvalidYearDayArrayValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Year day values must be between 1 and 366, or -1 and -366');
+
+        new YearDay([100, 367, -367]);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/ByTest.php b/tests/Unit/Domain/ValueObject/Recurrence/ByTest.php
new file mode 100644
index 00000000..1aa229b9
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/ByTest.php
@@ -0,0 +1,65 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Second;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Minute;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Hour;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Day;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\MonthDay;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\Month;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\YearDay;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\SetPosition;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\By\WeekNumber;
+use InvalidArgumentException;
+
+class ByTest extends TestCase
+{
+    public function testConstructorWithValidByValues(): void
+    {
+        $byArray = [
+            new Second([15]),
+            new Minute([30]),
+            new Hour([4]),
+            new Day([RecurrenceWeekDay::monday()]),
+            new MonthDay([15]),
+            new Month([6]),
+            new YearDay([200]),
+            new SetPosition([3]),
+            new WeekNumber([10]),
+        ];
+
+        $by = new By($byArray);
+
+        $this->assertInstanceOf(By::class, $by);
+        $expectedString = implode(';', array_map(static function ($byValue) {
+            return (string)$byValue;
+        }, $byArray));
+        $this->assertSame($expectedString, $by->__toString());
+    }
+
+    public function testConstructorWithInvalidByValues(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Values must be one of: Day, Hour, Minute, Month, MonthDay, Second, SetPosition, WeekNumber, YearDay');
+
+        $byArray = [
+            new Second([15]),
+            'InvalidValue',
+        ];
+
+        new By($byArray);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/CountTest.php b/tests/Unit/Domain/ValueObject/Recurrence/CountTest.php
new file mode 100644
index 00000000..b6cebb41
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/CountTest.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Count;
+use InvalidArgumentException;
+
+class CountTest extends TestCase
+{
+    public function testConstructorWithValidCount(): void
+    {
+        $count = new Count(5);
+
+        $this->assertInstanceOf(Count::class, $count);
+        $this->assertSame('COUNT=5', $count->__toString());
+    }
+
+    public function testConstructorWithInvalidCountValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Count must be greater than 0');
+
+        new Count(0);
+    }
+
+    public function testConstructorWithNegativeCountValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Count must be greater than 0');
+
+        new Count(-5);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/ExclusionTest.php b/tests/Unit/Domain/ValueObject/Recurrence/ExclusionTest.php
new file mode 100644
index 00000000..291af057
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/ExclusionTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use DateTime as PhpDateTime;
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Exclusion;
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+use InvalidArgumentException;
+
+class ExclusionTest extends TestCase
+{
+    public function testConstructorWithSingleExclusion(): void
+    {
+        $exclusion = new Exclusion([new DateTime(
+            new PhpDateTime('2023-12-31T12:00:00'),
+            true
+        )]);
+
+        $this->assertInstanceOf(Exclusion::class, $exclusion);
+        $this->assertSame('20231231T120000', $exclusion->__toString());
+    }
+
+    public function testConstructorWithMultipleExclusions(): void
+    {
+        $exclusions = new Exclusion([
+            new DateTime(new PhpDateTime('2023-12-31T12:00:00'), true),
+            new DateTime(new PhpDateTime('2023-12-30T14:30:00'), true),
+        ]);
+
+        $this->assertInstanceOf(Exclusion::class, $exclusions);
+        $this->assertSame('20231231T120000,20231230T143000', $exclusions->__toString());
+    }
+
+    public function testConstructorWithInvalidExclusionValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Values must be DateTime objects');
+
+        new Exclusion([new DateTime(new PhpDateTime('2023-12-31T12:00:00'), true), 'invalidValue']);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/FrequencyTest.php b/tests/Unit/Domain/ValueObject/Recurrence/FrequencyTest.php
new file mode 100644
index 00000000..d2582663
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/FrequencyTest.php
@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Frequency;
+use Eluceo\iCal\Domain\Enum\RecurrenceFrequency;
+
+class FrequencyTest extends TestCase
+{
+    public function testConstructorWithValidFrequency(): void
+    {
+        $frequency = new Frequency(RecurrenceFrequency::DAILY());
+
+        $this->assertInstanceOf(Frequency::class, $frequency);
+        $this->assertSame('FREQ=DAILY', $frequency->__toString());
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/IntervalTest.php b/tests/Unit/Domain/ValueObject/Recurrence/IntervalTest.php
new file mode 100644
index 00000000..a1763ebc
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/IntervalTest.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Interval;
+use InvalidArgumentException;
+
+class IntervalTest extends TestCase
+{
+    public function testConstructorWithValidInterval(): void
+    {
+        $interval = new Interval(2);
+
+        $this->assertInstanceOf(Interval::class, $interval);
+        $this->assertSame('INTERVAL=2', $interval->__toString());
+    }
+
+    public function testConstructorWithInvalidIntervalValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Interval must be greater than 0');
+
+        new Interval(0);
+    }
+
+    public function testConstructorWithNegativeIntervalValue(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Interval must be greater than 0');
+
+        new Interval(-2);
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/UntilTest.php b/tests/Unit/Domain/ValueObject/Recurrence/UntilTest.php
new file mode 100644
index 00000000..69ca4d62
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/UntilTest.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use DateTime as PhpDateTime;
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\Until;
+use Eluceo\iCal\Domain\ValueObject\DateTime;
+
+class UntilTest extends TestCase
+{
+    public function testConstructorWithValidDateTime(): void
+    {
+        $dateTime = new DateTime(new PhpDateTime('2023-12-31T12:00:00'), true);
+        $until = new Until($dateTime);
+
+        $this->assertInstanceOf(Until::class, $until);
+        $this->assertSame('UNTIL=20231231T120000', $until->__toString());
+    }
+}
diff --git a/tests/Unit/Domain/ValueObject/Recurrence/WeekStartTest.php b/tests/Unit/Domain/ValueObject/Recurrence/WeekStartTest.php
new file mode 100644
index 00000000..ef3a0fe9
--- /dev/null
+++ b/tests/Unit/Domain/ValueObject/Recurrence/WeekStartTest.php
@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) 2023 Markus Poerschke <markus@poerschke.nrw>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal\Unit\Domain\ValueObject\Recurrence;
+
+use PHPUnit\Framework\TestCase;
+use Eluceo\iCal\Domain\ValueObject\Recurrence\WeekStart;
+use Eluceo\iCal\Domain\Enum\RecurrenceWeekDay;
+
+class WeekStartTest extends TestCase
+{
+    public function testConstructorWithValidWeekStart(): void
+    {
+        $weekStart = new WeekStart(RecurrenceWeekDay::MONDAY());
+
+        $this->assertInstanceOf(WeekStart::class, $weekStart);
+        $this->assertSame('WKST=MO', $weekStart->__toString());
+    }
+}