diff --git a/lib/kaffy/resource_admin.ex b/lib/kaffy/resource_admin.ex
index 031aaedf..2c294502 100644
--- a/lib/kaffy/resource_admin.ex
+++ b/lib/kaffy/resource_admin.ex
@@ -2,6 +2,8 @@ defmodule Kaffy.ResourceAdmin do
   alias Kaffy.ResourceSchema
   alias Kaffy.Utils
 
+  @default_id_separator ":"
+
   @moduledoc """
   ResourceAdmin modules should be created for every schema you want to customize/configure in Kaffy.
 
@@ -148,7 +150,7 @@ defmodule Kaffy.ResourceAdmin do
   @doc """
   `ordering/1` takes a schema and returns how the entries should be ordered.
 
-  If `ordering/1` is not defined, Kaffy will return `[desc: :id]`.
+  If `ordering/1` is not defined, Kaffy will return `[desc: primary_key]`, or the first field of the primary key, if it's a composite.
 
   ## Examples
 
@@ -159,7 +161,10 @@ defmodule Kaffy.ResourceAdmin do
   ```
   """
   def ordering(resource) do
-    Utils.get_assigned_value_or_default(resource, :ordering, desc: :id)
+    schema = resource[:schema]
+    [order_key | _] = ResourceSchema.primary_keys(schema)
+
+    Utils.get_assigned_value_or_default(resource, :ordering, desc: order_key)
   end
 
   @doc """
@@ -331,6 +336,70 @@ defmodule Kaffy.ResourceAdmin do
     Utils.get_assigned_value_or_default(resource, :plural_name, default)
   end
 
+  @doc """
+  `serialize_id/2` takes a schema and record and must return a string to be used in the URL and form values.
+
+  If `serialize_id/2` is not defined, Kaffy will concatenate multiple primary keys with `":"` as a separator.
+
+  Examples:
+
+  ```elixir
+  # Default method with fixed keys
+  def serialize_id(_schema, record) do
+    Enum.join([record.post_id, record.tag_id], ":")
+  end
+
+  # ETF
+  def serialize_id(_schema, record) do
+    {record.post_id, record.tag_id}
+    |> :erlang.term_to_binary()
+    |> Base.url_encode64()
+  end
+  ```
+  """
+  def serialize_id(resource, entry) do
+    schema = resource[:schema]
+    default = schema
+      |> ResourceSchema.primary_keys()
+      |> Enum.map_join(@default_id_separator, &Map.get(entry, &1))
+
+    Utils.get_assigned_value_or_default(resource, :serialize_id, default, [entry])
+  end
+
+  @doc """
+  `deserialize_id/2` takes a schema and serialized id and must return a complete
+  keyword list in the form of [{:primary_key, value}, ...].
+
+  If `deserialize_id/2` is not defined, Kaffy will split multiple primary keys with `":"` as a separator.
+
+  Examples:
+
+  ```elixir
+  # Default method with fixed keys
+  def deserialize_id(_schema, serialized_id) do
+    Enum.zip([:post_id, :tag_id], String.split(serialized_id, ":"))
+  end
+
+  # Deserialize from ETF
+  def deserialize_id(_schema, serialized_id) do
+    {product_id, tag_id} = serialized_id
+    |> Base.url_decode64!()
+    |> :erlang.binary_to_term()
+
+    [product_id: product_id, tag_id: tag_id]
+  end
+  ```
+  """
+  def deserialize_id(resource, id) do
+    schema = resource[:schema]
+    id_list = String.split(id, @default_id_separator)
+    default = schema
+      |> ResourceSchema.primary_keys()
+      |> Enum.zip(id_list)
+
+    Utils.get_assigned_value_or_default(resource, :deserialize_id, default, [id])
+  end
+
   def resource_actions(resource, conn) do
     Utils.get_assigned_value_or_default(resource, :resource_actions, nil, [conn], false)
   end
diff --git a/lib/kaffy/resource_form.ex b/lib/kaffy/resource_form.ex
index 4452456f..d2354fc9 100644
--- a/lib/kaffy/resource_form.ex
+++ b/lib/kaffy/resource_form.ex
@@ -47,8 +47,14 @@ defmodule Kaffy.ResourceForm do
         opts
       end
 
+    # Check if any primary key fields are nil
+    is_create_event = changeset.data.__struct__
+      |> Kaffy.ResourceSchema.primary_keys()
+      |> Enum.map(&Map.get(changeset.data, &1))
+      |> Enum.any?(&is_nil/1)
+
     permission =
-      case is_nil(changeset.data.id) do
+      case is_create_event do
         true -> Map.get(options, :create, :editable)
         false -> Map.get(options, :update, :editable)
       end
@@ -115,13 +121,13 @@ defmodule Kaffy.ResourceForm do
         textarea(form, field, [value: value, rows: 4, placeholder: "JSON Content"] ++ opts)
 
       :id ->
-        case Kaffy.ResourceSchema.primary_key(schema) == [field] do
+        case field in Kaffy.ResourceSchema.primary_keys(schema) do
           true -> text_input(form, field, opts)
           false -> text_or_assoc(conn, schema, form, field, opts)
         end
 
       :binary_id ->
-        case Kaffy.ResourceSchema.primary_key(schema) == [field] do
+        case field in Kaffy.ResourceSchema.primary_keys(schema) do
           true -> text_input(form, field, opts)
           false -> text_or_assoc(conn, schema, form, field, opts)
         end
diff --git a/lib/kaffy/resource_query.ex b/lib/kaffy/resource_query.ex
index c2a03973..298d134d 100644
--- a/lib/kaffy/resource_query.ex
+++ b/lib/kaffy/resource_query.ex
@@ -52,7 +52,9 @@ defmodule Kaffy.ResourceQuery do
 
   def fetch_resource(conn, resource, id) do
     schema = resource[:schema]
-    query = from(s in schema, where: s.id == ^id)
+
+    id_filter = Kaffy.ResourceAdmin.deserialize_id(resource, id)
+    query = from(s in schema, where: ^id_filter)
 
     case Kaffy.ResourceAdmin.custom_show_query(conn, resource, query) do
       {custom_query, opts} -> Kaffy.Utils.repo().one(custom_query, opts)
@@ -65,8 +67,13 @@ defmodule Kaffy.ResourceQuery do
   def fetch_list(resource, ids) do
     schema = resource[:schema]
 
-    from(s in schema, where: s.id in ^ids)
-    |> Kaffy.Utils.repo().all()
+    primary_keys = Kaffy.ResourceSchema.primary_keys(schema)
+    ids = Enum.map(ids, &Kaffy.ResourceAdmin.deserialize_id(resource, &1))
+
+    case build_list_query(schema, primary_keys, ids) do
+      {:error, error_msg} -> {:error, error_msg}
+      query -> Kaffy.Utils.repo().all(query)
+    end
   end
 
   def total_count(schema, do_cache, query, opts \\ [])
@@ -149,6 +156,21 @@ defmodule Kaffy.ResourceQuery do
     {query, limited_query}
   end
 
+  defp build_list_query(_schema, [], _key_pairs) do
+    {:error, "No private keys. List action not supported."}
+  end
+
+  defp build_list_query(schema, [primary_key], ids) do
+    ids = Enum.map(ids, fn [{_key, id}] -> id end)
+    from(s in schema, where: field(s, ^primary_key) in ^ids)
+  end
+
+  defp build_list_query(schema, _composite_key, key_pairs) do
+    Enum.reduce(key_pairs, schema, fn pair, query_acc ->
+      from query_acc, or_where: ^pair
+    end)
+  end
+
   defp build_filtered_fields_query(query, []), do: query
 
   defp build_filtered_fields_query(query, [filter | rest]) do
diff --git a/lib/kaffy/resource_schema.ex b/lib/kaffy/resource_schema.ex
index 57ab23bd..ede7f90d 100644
--- a/lib/kaffy/resource_schema.ex
+++ b/lib/kaffy/resource_schema.ex
@@ -1,7 +1,7 @@
 defmodule Kaffy.ResourceSchema do
   @moduledoc false
 
-  def primary_key(schema) do
+  def primary_keys(schema) do
     schema.__schema__(:primary_key)
   end
 
@@ -26,7 +26,10 @@ defmodule Kaffy.ResourceSchema do
   end
 
   def form_fields(schema) do
-    to_be_removed = fields_to_be_removed(schema) ++ [:id, :inserted_at, :updated_at]
+    to_be_removed =
+      fields_to_be_removed(schema) ++
+        primary_keys(schema) ++
+        [:inserted_at, :updated_at]
     Keyword.drop(fields(schema), to_be_removed)
   end
 
@@ -35,7 +38,9 @@ defmodule Kaffy.ResourceSchema do
       fields_to_be_removed(schema) ++
         get_has_many_associations(schema) ++
         get_has_one_assocations(schema) ++
-        get_many_to_many_associations(schema) ++ [:id, :inserted_at, :updated_at]
+        get_many_to_many_associations(schema) ++
+        primary_keys(schema) ++
+        [:inserted_at, :updated_at]
 
     Keyword.drop(fields(schema), to_be_removed)
   end
diff --git a/lib/kaffy_web/controllers/resource_controller.ex b/lib/kaffy_web/controllers/resource_controller.ex
index ccc9bf88..e501153a 100644
--- a/lib/kaffy_web/controllers/resource_controller.ex
+++ b/lib/kaffy_web/controllers/resource_controller.ex
@@ -349,11 +349,14 @@ defmodule KaffyWeb.ResourceController do
     action_record = get_action_record(actions, action_key)
     kaffy_inputs = Map.get(params, "kaffy-input", %{})
 
-    result =
-      case Map.get(action_record, :inputs, []) do
-        [] -> action_record.action.(conn, entries)
-        _ -> action_record.action.(conn, entries, kaffy_inputs)
-      end
+    result = case entries do
+      {:error, error_msg} -> {:error, error_msg}
+      entries ->
+        case Map.get(action_record, :inputs, []) do
+          [] -> action_record.action.(conn, entries)
+          _ -> action_record.action.(conn, entries, kaffy_inputs)
+        end
+    end
 
     case result do
       :ok ->
@@ -391,6 +394,9 @@ defmodule KaffyWeb.ResourceController do
   end
 
   defp redirect_to_resource(conn, context, resource, entry) do
+    my_resource = Kaffy.Utils.get_resource(conn, context, resource)
+    id = Kaffy.ResourceAdmin.serialize_id(my_resource, entry)
+
     redirect(conn,
       to:
         Kaffy.Utils.router().kaffy_resource_path(
@@ -398,7 +404,7 @@ defmodule KaffyWeb.ResourceController do
           :show,
           context,
           resource,
-          entry.id
+          id
         )
     )
   end
diff --git a/lib/kaffy_web/templates/resource/_table.html.eex b/lib/kaffy_web/templates/resource/_table.html.eex
index 2abcc2f8..e81de33d 100644
--- a/lib/kaffy_web/templates/resource/_table.html.eex
+++ b/lib/kaffy_web/templates/resource/_table.html.eex
@@ -4,17 +4,17 @@
     </thead>
 
     <tbody>
-        <%= for entry <- @entries do %>
+        <%= for {entry, index} <- Enum.with_index(@entries) do %>
             <tr>
                 <td>
                     <div class="custom-control custom-checkbox">
-                        <input type="checkbox" class="custom-control-input select-item kaffy-resource-checkbox" id="kaffy-select-<%= entry.id %>" name="resource" value="<%= entry.id %>"/>
-                        <label class="custom-control-label" for="kaffy-select-<%= entry.id %>"></label>
+                        <input type="checkbox" class="custom-control-input select-item kaffy-resource-checkbox" id="kaffy-select-<%= index %>" name="resource" value="<%= Kaffy.ResourceAdmin.serialize_id(@my_resource, entry) %>"/>
+                        <label class="custom-control-label" for="kaffy-select-<%= index %>"></label>
                     </div>
                 </td>
                 <%= for {field, index} <- Enum.with_index(@fields) do %>
                     <%= if index == 0 do %>
-                        <td><%= link Kaffy.ResourceSchema.kaffy_field_value(@conn, entry, field), to: Kaffy.Utils.router().kaffy_resource_path(@conn, :show, @context, @resource, entry.id) %></td>
+                        <td><%= link Kaffy.ResourceSchema.kaffy_field_value(@conn, entry, field), to: Kaffy.Utils.router().kaffy_resource_path(@conn, :show, @context, @resource, Kaffy.ResourceAdmin.serialize_id(@my_resource, entry)) %></td>
                     <% else %>
                         <td><%= Kaffy.ResourceSchema.kaffy_field_value(@conn, entry, field) %></td>
                     <% end %>
diff --git a/lib/kaffy_web/templates/resource/show.html.eex b/lib/kaffy_web/templates/resource/show.html.eex
index d8336965..d6960a22 100644
--- a/lib/kaffy_web/templates/resource/show.html.eex
+++ b/lib/kaffy_web/templates/resource/show.html.eex
@@ -9,7 +9,7 @@
         <div class="card-header">
             <div class="row justify-content-between">
                 <div class="col-auto mr-auto">
-                    <h1><%= @resource_name %> #<%= @changeset.data.id %></h1>
+                    <h1><%= @resource_name %> #<%= Kaffy.ResourceAdmin.serialize_id(@my_resource, @changeset.data) %></h1>
                 </div>
                 <div class="col-auto">
                     <%= if Kaffy.ResourceAdmin.resource_actions(@my_resource, @conn) do %>
@@ -20,7 +20,7 @@
                                 </button>
                                 <div class="dropdown-menu">
                                     <%= for {action_key, options} <- Kaffy.ResourceAdmin.resource_actions(@my_resource, @conn) do %>
-                                        <%= form_tag(Kaffy.Utils.router().kaffy_resource_path(@conn, :single_action, @context, @resource, @changeset.data.id, to_string(action_key)), method: :post) %>
+                                        <%= form_tag(Kaffy.Utils.router().kaffy_resource_path(@conn, :single_action, @context, @resource, Kaffy.ResourceAdmin.serialize_id(@my_resource, @changeset.data), to_string(action_key)), method: :post) %>
                                             <input type="submit" name="submit" value="<%= options.name %>" class="dropdown-item" />
                                         </form>
                                     <% end %>
@@ -32,7 +32,7 @@
             </div>
         </div>
         <div class="card-body">
-            <%= form_for @changeset, Kaffy.Utils.router().kaffy_resource_path(@conn, :update, @context, @resource, @changeset.data.id), [method: :put, multipart: true], fn f -> %>
+            <%= form_for @changeset, Kaffy.Utils.router().kaffy_resource_path(@conn, :update, @context, @resource, Kaffy.ResourceAdmin.serialize_id(@my_resource, @changeset.data)), [method: :put, multipart: true], fn f -> %>
                 <%= for {field, options} <- Kaffy.ResourceAdmin.form_fields(@my_resource) do %>
                     <%= if options.update != :hidden do %>
                         <%= Kaffy.ResourceForm.kaffy_input @conn, @changeset, f, field, options %>
@@ -53,7 +53,7 @@
     </div>
 
     <!-- Modal -->
-    <%= form_for @changeset, Kaffy.Utils.router().kaffy_resource_path(@conn, :delete, @context, @resource, @changeset.data.id), [method: :delete], fn _f -> %>
+    <%= form_for @changeset, Kaffy.Utils.router().kaffy_resource_path(@conn, :delete, @context, @resource, Kaffy.ResourceAdmin.serialize_id(@my_resource, @changeset.data)), [method: :delete], fn _f -> %>
         <div class="modal fade" id="delete-modal" tabindex="-1" role="dialog" aria-labelledby="delete-modal-label" aria-hidden="true">
             <div class="modal-dialog" role="document">
                 <div class="modal-content">
diff --git a/test/actions_test.exs b/test/actions_test.exs
index 894b1a71..96deffd8 100644
--- a/test/actions_test.exs
+++ b/test/actions_test.exs
@@ -67,6 +67,35 @@ defmodule ActionsTest do
     end
   end
 
+  defmodule ActionsCompositeKeyAdmin do
+    @string_action "test_action"
+    @response %{product_id: 1, tag_id: 1}
+
+    def index(_), do: []
+
+    def resource_actions(_conn) do
+      %{
+        @string_action => %{
+          name: "Test Action",
+          action: fn _, _ ->
+            {:ok, @response}
+          end
+        }
+      }
+    end
+
+    def list_actions(_conn) do
+      %{
+        @string_action => %{
+          name: "Test Action",
+          action: fn _, _ ->
+            :ok
+          end
+        }
+      }
+    end
+  end
+
   defmodule FakeSchema do
     use Ecto.Schema
 
@@ -99,6 +128,12 @@ defmodule ActionsTest do
           resources: [
             test: [schema: FakeSchema, admin: ActionsMapAdmin]
           ]
+        ],
+        composite: [
+          name: "composite",
+          resources: [
+            test: [schema: KaffyTest.Schemas.Owner, admin: ActionsCompositeKeyAdmin]
+          ]
         ]
       ]
     end)
@@ -140,4 +175,32 @@ defmodule ActionsTest do
       assert %{"success" => _} = get_flash(result_conn)
     end
   end
+
+  test "single action handles composite primary keys", %{conn: conn} do
+    with_mock Kaffy.ResourceQuery, fetch_resource: fn _, _, _ -> %{product_id: 1, tag_id: 1} end do
+      result_conn =
+        ResourceController.single_action(conn, %{
+          "context" => "composite",
+          "resource" => "test",
+          "action_key" => "test_action",
+          "id" => "1:1"
+        })
+
+      assert %{"success" => _} = get_flash(result_conn)
+    end
+  end
+
+  test "list action handles composite primary keys", %{conn: conn} do
+    with_mock Kaffy.ResourceQuery, fetch_list: fn _, _ -> [%{product_id: 1, tag_id: 1}, %{product_id: 1, tag_id: 2}] end do
+      result_conn =
+        ResourceController.list_action(conn, %{
+          "context" => "composite",
+          "resource" => "test",
+          "action_key" => "test_action",
+          "id" => "1:1,1:2"
+        })
+
+      assert %{"success" => _} = get_flash(result_conn)
+    end
+  end
 end
diff --git a/test/kaffy_test.exs b/test/kaffy_test.exs
index 968c6ce8..13f4bee5 100644
--- a/test/kaffy_test.exs
+++ b/test/kaffy_test.exs
@@ -1,7 +1,7 @@
 defmodule KaffyTest do
   use ExUnit.Case
-  alias KaffyTest.Schemas.{Company, Person, Pet}
-  # alias KaffyTest.Admin.PersonAdmin
+  
+  alias KaffyTest.Schemas.{Company, Person, Pet, Owner}
 
   test "creating a person" do
     person = %Person{}
@@ -24,8 +24,12 @@ defmodule KaffyTest do
     end
 
     test "primary_key/1 should return a primary key" do
-      assert [:id] == ResourceSchema.primary_key(Person)
-      assert [:id] == ResourceSchema.primary_key(Pet)
+      assert [:id] == ResourceSchema.primary_keys(Person)
+      assert [:id] == ResourceSchema.primary_keys(Pet)
+    end
+
+    test "primary_key/1 should return a composite key" do
+      assert [:person_id, :pet_id] == ResourceSchema.primary_keys(Owner)
     end
 
     test "kaffy_field_name/2 should return the name of the field" do
diff --git a/test/resource_admin_test.exs b/test/resource_admin_test.exs
index 39e3ded3..f17f3cfc 100644
--- a/test/resource_admin_test.exs
+++ b/test/resource_admin_test.exs
@@ -1,6 +1,7 @@
 defmodule Kaffy.ResourceAdminTest do
   use ExUnit.Case, async: true
   alias Kaffy.ResourceAdmin
+  alias KaffyTest.Schemas.{Owner, Pet}
 
   defmodule Cactus do
   end
@@ -17,6 +18,28 @@ defmodule Kaffy.ResourceAdminTest do
     def index_description(_), do: "Person Admin Description"
   end
 
+  defmodule PetAdmin do
+  end
+
+  defmodule OwnerAdmin do
+  end
+
+  defmodule OwnerETFAdmin do
+    def serialize_id(_schema, owner) do
+      {owner.person_id, owner.pet_id}
+      |> :erlang.term_to_binary()
+      |> Base.url_encode64(padding: false)
+    end
+
+    def deserialize_id(_schema, serialized_id) do
+      {person_id, pet_id} = serialized_id
+      |> Base.url_decode64!(padding: false)
+      |> :erlang.binary_to_term()
+
+      [person_id: person_id, pet_id: pet_id]
+    end
+  end
+
   defmodule Nested.Node do
   end
 
@@ -46,6 +69,34 @@ defmodule Kaffy.ResourceAdminTest do
     end
   end
 
+  describe "serialize_id/2" do
+    test "serialize standard id" do
+      assert ResourceAdmin.serialize_id([schema: Pet, admin: PetAdmin], %{id: 1}) == "1"
+    end
+
+    test "serialize composite id" do
+      assert ResourceAdmin.serialize_id([schema: Owner, admin: OwnerAdmin], %{person_id: 1, pet_id: 2}) == "1:2"
+    end
+
+    test "custom serialization of composite key" do
+      assert ResourceAdmin.serialize_id([schema: Owner, admin: OwnerETFAdmin], %{person_id: 1, pet_id: 2}) == "g2gCYQFhAg"
+    end
+  end
+
+  describe "deserialize_id/2" do
+    test "deserialize standard id" do
+      assert ResourceAdmin.deserialize_id([schema: Pet, admin: PetAdmin], "1") == [id: "1"]
+    end
+
+    test "deserialize composite id" do
+      assert ResourceAdmin.deserialize_id([schema: Owner, admin: OwnerAdmin], "1:2") == [person_id: "1", pet_id: "2"]
+    end
+
+    test "custom deserialization of composite key" do
+      assert ResourceAdmin.deserialize_id([schema: Owner, admin: OwnerETFAdmin], "g2gCYQFhAg") == [person_id: 1, pet_id: 2]
+    end
+  end
+  
   describe "index_description/1" do
     test "nil if index_description is not defined as function in admin" do
       refute ResourceAdmin.index_description(schema: Nested.Node, admin: NestedNodeAdmin)
diff --git a/test/test_helper.exs b/test/test_helper.exs
index d937da19..76ac6a04 100644
--- a/test/test_helper.exs
+++ b/test/test_helper.exs
@@ -43,3 +43,13 @@ defmodule KaffyTest.Schemas.Company do
     has_many(:people, KaffyTest.Schemas.Person)
   end
 end
+
+defmodule KaffyTest.Schemas.Owner do
+  use Ecto.Schema
+
+  @primary_key false
+  schema "owner" do
+    field :person_id, :id, primary_key: true
+    field :pet_id, :id, primary_key: true
+  end
+end