diff --git a/snooty.toml b/snooty.toml
index b4c9f5f9..789f516a 100644
--- a/snooty.toml
+++ b/snooty.toml
@@ -17,6 +17,7 @@ toc_landing_pages = [
 [constants]
 rails-6-version = 6.0
 rails-7-version = 7.1
+rails-8-version-docs = "v8.0"
 odm = "Mongoid"
 version = "9.0"
 full-version = "{+version+}.2"
diff --git a/source/data-modeling.txt b/source/data-modeling.txt
index ba6be34e..50af17cf 100644
--- a/source/data-modeling.txt
+++ b/source/data-modeling.txt
@@ -13,13 +13,13 @@ Model Your Data
 
 .. toctree::
    :caption: Data Modeling
-
-In this section, you can learn how to model data in {+odm+}.
-
+   
    Documents </data-modeling/documents>
    Field Behaviors </data-modeling/field-behaviors>
    Inheritance </data-modeling/inheritance>
-   Nested Attributes </data-modeling/nested-attributes>
+   Document Validation </data-modeling/validation>
+
+In this section, you can learn how to model data in {+odm+}.
 
 - :ref:`mongoid-modeling-documents`: Learn about the ``Document``
   module.
@@ -30,5 +30,5 @@ In this section, you can learn how to model data in {+odm+}.
 - :ref:`mongoid-modeling-inheritance`: Learn how to implement
   inheritance in your model classes.
 
-- :ref:`mongoid-modeling-nested-attr`: Learn how to modify documents and
-  their associations in a single operation.
+- :ref:`mongoid-modeling-validation`: Learn how to create document
+  validation rules for your model classes.
diff --git a/source/data-modeling/validation.txt b/source/data-modeling/validation.txt
new file mode 100644
index 00000000..9f96c72f
--- /dev/null
+++ b/source/data-modeling/validation.txt
@@ -0,0 +1,343 @@
+.. _mongoid-modeling-validation:
+
+===================
+Document Validation
+===================
+
+.. facet::
+   :name: genre
+   :values: reference
+
+.. meta::
+   :keywords: ruby framework, odm, schema, code example
+
+.. contents:: On this page
+   :local:
+   :backlinks: none
+   :depth: 2
+   :class: singlecol
+
+Overview
+--------
+
+In this guide, you can learn how to define **validation rules** in your
+{+odm+} models. After you implement validation into your models, {+odm+}
+prevents you from running write operations that violate the validation
+rules. Use document validation to restrict data types and value ranges
+of document fields in your collections.
+
+{+odm+} includes ``ActiveModel::Validations`` from Active Record to
+provide validation functionality, including an associated and uniqueness
+validator. To learn more, see the `Active Record Validations
+<https://guides.rubyonrails.org/active_record_validations.html>`__
+Rails guide and `ActiveModel::Validations
+<https://api.rubyonrails.org/classes/ActiveModel/Validations.html>`__
+Rails API documentation.
+
+.. note:: Comparing {+odm+} and MongoDB Validation
+
+   Validation in {+odm+} applies only in the context of your
+   application and differs from creating schema validation rules in
+   MongoDB. This means that your validation rules do not apply to write
+   operations that are performed outside of your application. To learn
+   more about MongoDB schema validation, see :manual:`Schema Validation
+   </core/schema-validation/>` in the {+server-manual+}.
+
+Validation Helpers
+------------------
+
+{+odm+} supports Active Record validation helpers that you can use when defining your
+model classes. You can use these helpers to set common validation rules
+in your application, such as checking for the presence of a field,
+comparing a field value to a specified value, or ensuring that a field
+has a unique value.
+
+Define a Validation Rule
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Use the ``validates`` macro to create a validation rule, then include
+the validation helper and the required specifications for the rule.
+
+.. tip::
+    
+   Each validation helper accepts one or more field names, which allows you
+   to define the same rule for multiple fields.
+
+The following code demonstrates how to use the ``presence`` validation
+helper to require that ``Person`` instances contain a value for the
+``name`` field:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-simple-val
+   :end-before: end-simple-val
+   :language: ruby
+   :emphasize-lines: 5
+   :dedent:
+
+You can learn about other useful validation helpers in the
+:ref:`mongoid-common-validations` section of this guide.
+
+.. _mongoid-common-validations:
+
+Common Validations
+------------------
+
+In this section, you can learn about the following common validation
+rules and view examples that use validation helpers:
+
+- :ref:`mongoid-compare-validation`
+- :ref:`mongoid-format-validation`
+- :ref:`mongoid-inclusion-exclusion-validation`
+- :ref:`mongoid-presence-absence-validation`
+- :ref:`mongoid-uniqueness-validation`
+- :ref:`mongoid-association-validation`
+- :ref:`mongoid-other-validation`
+
+.. _mongoid-compare-validation:
+
+Comparison Rule
+~~~~~~~~~~~~~~~
+
+You can use the ``comparison`` helper to validate a document based on
+the value of a specified field.
+
+The ``comparison`` helper supports the following options:
+
+- ``greater_than``: The value must be greater than the supplied value.
+- ``greater_than_or_equal_to``: The value must be greater than or equal to the supplied value.
+- ``equal_to``: The value must be equal to the supplied value.
+- ``less_than``: The value must be less than the supplied value.
+- ``less_than_or_equal_to``: The value must be less than or equal to the supplied value.
+- ``other_than``: The value must be different than the supplied value.
+
+This example defines the following comparison validation rules on the
+``Order`` model:
+
+- ``delivery_date``: Must be after (greater than) the value of ``order_date``
+- ``quantity``: Must be less than ``5``
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-comparison
+   :end-before: end-comparison
+   :language: ruby
+   :emphasize-lines: 8-9
+   :dedent:
+
+.. _mongoid-format-validation:
+
+Formatting Rule
+~~~~~~~~~~~~~~~
+
+You can use the ``format`` helper to validate a document based on
+whether a field value matches a regular expression. Use the ``with``
+option to specify the regular expression.
+
+This example defines a format validation rule on the
+``User`` model to ensure that the ``username`` field contains only
+letters:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-fmt
+   :end-before: end-fmt
+   :language: ruby
+   :emphasize-lines: 6
+   :dedent:
+
+.. tip:: Alternative Helper Method
+
+   The ``Mongoid::Document`` module provides macro methods for certain
+   validations. Instead of using the ``format`` validation helper in the
+   ``validates`` macro statement, you can use the
+   ``validates_format_of`` method, as shown in the following code:
+
+   .. code-block:: ruby
+
+      validates_format_of :username, with: /\A[a-zA-Z]+\z/
+
+.. _mongoid-inclusion-exclusion-validation:
+
+Inclusion or Exclusion Rule
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can use the ``inclusion`` and ``exclusion`` helpers to validate a
+document based on whether a field value is in a specified list
+of values. Use the ``in`` option to specify the list of values.
+
+This example defines an inclusion validation rule on the
+``Order`` model to ensure that the ``shipping`` field value is one of
+the accepted values:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-inclusion
+   :end-before: end-inclusion
+   :language: ruby
+   :emphasize-lines: 6
+   :dedent:
+
+.. _mongoid-presence-absence-validation:
+
+Presence or Absence Rule
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can use the ``presence`` and ``absence`` helpers to validate a
+document based on whether a field value is present or absent (empty).
+
+This example defines an absence validation rule on the
+``Order`` model to ensure that the ``delivery_date`` field value is
+either ``nil`` or an empty string:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-absence
+   :end-before: end-absence
+   :language: ruby
+   :emphasize-lines: 6
+   :dedent:
+
+.. tip:: Alternative Helper Method
+
+   The ``Mongoid::Document`` module provides macro methods for certain
+   validations. Instead of using the ``presence`` validation helper in the
+   ``validates`` macro statement, you can use the
+   ``validates_presence_of`` method, as shown in the following code:
+
+   .. code-block:: ruby
+
+      validates_presence_of :delivery_date
+
+.. _mongoid-uniqueness-validation:
+
+Uniqueness Rule
+~~~~~~~~~~~~~~~
+
+You can use the ``uniqueness`` helper to validate a
+document based on whether a field value is unique from other values in
+the collection. You can use the ``scope`` option to specify one or more
+field names that {+odm+} uses to limit the uniqueness check.
+
+This example defines a uniqueness validation rule on the
+``Person`` model to ensure that the ``first_name`` field value is
+unique within documents that have the same ``last_name`` value:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-unique
+   :end-before: end-unique
+   :language: ruby
+   :emphasize-lines: 7
+   :dedent:
+
+.. tip:: Alternative Helper Method
+
+   The ``Mongoid::Document`` module provides macro methods for certain
+   validations. Instead of using the ``uniqueness`` validation helper in the
+   ``validates`` macro statement, you can use the
+   ``validates_uniqueness_of`` method, as shown in the following code:
+
+   .. code-block:: ruby
+
+      validates_uniqueness_of :first_name
+   
+   {+odm+} uses a ``primary`` read preference when you use the
+   ``validates_uniqueness_of`` method on a model, because if it
+   queries a secondary member of the replica set, it might read stale data.
+
+   This method takes a ``conditions`` option that allows you to specify
+   conditions to add when {+odm+} checks for uniqueness:
+
+   .. code-block:: ruby
+
+      validates_uniqueness_of :name, conditions: -> { where(:age.gte => 10) }
+
+.. _mongoid-association-validation:
+
+Validate Associations
+~~~~~~~~~~~~~~~~~~~~~
+
+You can use the ``validates_associated`` helper to validate any
+associations that your model has. When you include this validation rule,
+{+odm+} validates any association documents any time you try to
+save an instance.
+
+.. TODO link to associations page
+
+This example defines an association validation rule on the
+``Author`` model to run the validation rules for the embedded ``Book``
+instances:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-assoc
+   :end-before: end-assoc
+   :language: ruby
+   :emphasize-lines: 6
+   :dedent:
+
+.. important::
+
+   Don't use the ``validates_associated`` helper on both ends of your
+   associations because this causes {+odm+} to perform validations in an
+   infinite loop.
+
+.. _mongoid-other-validation:
+
+Custom Validation Rules
+~~~~~~~~~~~~~~~~~~~~~~~
+
+You can use the ``validates_each`` and ``validates_with`` helpers to
+create custom validators. To learn more about these helpers and view
+examples, see the `validates_each
+<https://guides.rubyonrails.org/active_record_validations.html#validates-each>`__
+and `validates_with
+<https://guides.rubyonrails.org/active_record_validations.html#validates-with>`__
+references in the Active Record documentation.
+
+To learn more about custom validators, see `Performing Custom
+Validations
+<https://guides.rubyonrails.org/active_record_validations.html#performing-custom-validations>`__
+in the Active Record documentation.
+
+Behavior
+--------
+
+{+odm+} performs validation when you persist, or save, a document to the
+database. The following methods trigger your validation rules, so
+{+odm+} saves the object to the database only if it passes validation:
+
+- ``create()``
+- ``save()``
+- ``update()``
+
+When you use the ``-!`` suffixed version of the preceding methods,
+{+odm+} returns an ``Mongoid::Errors::Validations`` exception if
+validation fails for an object.
+
+Trigger Validation
+~~~~~~~~~~~~~~~~~~
+
+You can run validations manually by using the ``valid?()`` method. This
+method returns ``true`` if the object passes validation, and
+``false`` otherwise:
+
+.. literalinclude:: /includes/data-modeling/validation.rb
+   :start-after: start-valid
+   :end-before: end-valid
+   :language: ruby
+   :emphasize-lines: 7, 11, 14
+   :dedent:
+
+{+odm+} behaves differently from Active Record when running ``valid?()``
+on persisted data. Active Record's ``valid?()`` runs all
+validations, but {+odm+}'s ``valid?()`` runs validations only on
+documents that are in memory to optimize performance.
+
+Additional Information
+----------------------
+
+To learn more about validation methods and macros in {+odm+}, see the
+:mongoid-api:`Mongoid::Validatable <Mongoid/Validatable.html>` module
+reference in the API documentation.
+
+To view a full list of validations helpers in Active Record, see the
+`ActiveModel::Validations::HelperMethods
+<https://api.rubyonrails.org/classes/ActiveModel/Validations/HelperMethods.html>`__
+reference in the Rails API documentation.
+
+.. TODO link to field types guide.
diff --git a/source/includes/data-modeling/validation.rb b/source/includes/data-modeling/validation.rb
new file mode 100644
index 00000000..47b51e27
--- /dev/null
+++ b/source/includes/data-modeling/validation.rb
@@ -0,0 +1,89 @@
+# start-simple-val
+class Person
+  include Mongoid::Document
+  
+  field :name, type: String
+  validates :name, presence: true
+end
+# end-simple-val
+
+# start-comparison
+class Order
+  include Mongoid::Document
+  
+  field :order_date, type: DateTime
+  field :delivery_date, type: DateTime
+  field :quantity, type: Integer
+
+  validates :delivery_date, comparison: { greater_than: :order_date }
+  validates :quantity, comparison: { less_than: 5 }
+end
+# end-comparison
+
+# start-fmt
+class User
+  include Mongoid::Document
+  
+  field :username, type: String
+
+  validates :username, format: { with: /\A[a-zA-Z]+\z/ }
+end
+# end-fmt
+
+# start-inclusion
+class Order
+  include Mongoid::Document
+  
+  field :shipping, type: String
+
+  validates :shipping, inclusion: { in: %w(standard priority overnight) }
+end
+# end-inclusion
+
+# start-absence
+class Order
+  include Mongoid::Document
+  
+  field :delivery_date, type: String
+
+  validates :delivery_date, absence: true
+end
+# end-absence
+
+# start-unique
+class Person
+  include Mongoid::Document
+  
+  field :first_name, type: String
+  field :last_name, type: String
+
+  validates :first_name, uniqueness: { scope: :last_name }
+end
+# end-unique
+
+# start-assoc
+class Author
+  include Mongoid::Document
+  
+  embeds_many :books
+
+  validates_associated :books
+end
+# end-assoc
+
+# start-valid
+class Person
+  include Mongoid::Document
+  
+  field :name, type: String
+  field :age, type: Integer
+
+  validates :age, comparison: { greater_than_or_equal_to: 0 }
+end
+
+# Returns true
+Person.new(name: "Berta Odom", age: 4).valid?
+
+# Returns false
+Person.new(name: "Cody Peng", age: -5).valid?
+# end-valid
\ No newline at end of file
diff --git a/source/interact-data.txt b/source/interact-data.txt
index b11a2b05..2e3e3707 100644
--- a/source/interact-data.txt
+++ b/source/interact-data.txt
@@ -18,6 +18,7 @@ Interact with Data
    Modify Query Results </interact-data/modify-results>
    Search Text </interact-data/text-search>
    Transactions and Sessions </interact-data/transaction>
+   Nested Attributes </interact-data/nested-attributes>
 
 In this section, you can learn how to use {+odm+} to interact with your
 MongoDB data.
@@ -32,4 +33,7 @@ MongoDB data.
   searches on text fields.
 
 - :ref:`mongoid-data-txn`: Learn how to perform multi-document
-  transactions to make atomic data changes.
\ No newline at end of file
+  transactions to make atomic data changes.
+
+- :ref:`mongoid-data-nested-attr`: Learn how to modify documents and
+  their associations in a single operation.
\ No newline at end of file
diff --git a/source/data-modeling/nested-attributes.txt b/source/interact-data/nested-attributes.txt
similarity index 99%
rename from source/data-modeling/nested-attributes.txt
rename to source/interact-data/nested-attributes.txt
index 7e8296d2..fcd10dd9 100644
--- a/source/data-modeling/nested-attributes.txt
+++ b/source/interact-data/nested-attributes.txt
@@ -1,4 +1,4 @@
-.. _mongoid-modeling-nested-attr:
+.. _mongoid-data-nested-attr:
 
 =================
 Nested Attributes