diff --git a/CHANGELOG.md b/CHANGELOG.md
index f870df96..5692fe54 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,10 @@
 
 * Require rails >= 3.2.
 
+* Serializers for associations are being looked up in a parent serializer's namespace first. Same with controllers' namespaces.
+
+* Added a "prefix" option in case you want to use a different version of serializer.
+
 # VERSION 0.8.1
 
 * Fix bug whereby a serializer using 'options' would blow up.
diff --git a/lib/action_controller/serialization.rb b/lib/action_controller/serialization.rb
index 5b1ee4ee..d86b2ac0 100644
--- a/lib/action_controller/serialization.rb
+++ b/lib/action_controller/serialization.rb
@@ -57,6 +57,18 @@ module ActionController
 
     private
 
+    def namespace_for_serializer
+      @namespace_for_serializer ||= self.class.parent unless self.class.parent == Object
+    end
+
+    def default_serializer(resource)
+      options = {}.tap do |o|
+        o[:namespace] = namespace_for_serializer if namespace_for_serializer
+      end
+
+      ActiveModel::Serializer.serializer_for(resource, options)
+    end
+
     def default_serializer_options
       {}
     end
@@ -69,9 +81,13 @@ module ActionController
     def build_json_serializer(resource, options = {})
       options = default_serializer_options.merge(options)
 
-      if serializer = options.fetch(:serializer, ActiveModel::Serializer.serializer_for(resource))
+      if serializer = options.fetch(:serializer, default_serializer(resource))
         options[:scope] = serialization_scope unless options.has_key?(:scope)
-        options[:resource_name] = controller_name if resource.respond_to?(:to_ary)
+
+        if resource.respond_to?(:to_ary)
+          options[:resource_name] = controller_name 
+          options[:namespace] = namespace_for_serializer if namespace_for_serializer
+        end
 
         serializer.new(resource, options)
       end
diff --git a/lib/active_model/array_serializer.rb b/lib/active_model/array_serializer.rb
index fe985e8b..e0c3ecfc 100644
--- a/lib/active_model/array_serializer.rb
+++ b/lib/active_model/array_serializer.rb
@@ -22,6 +22,7 @@ module ActiveModel
       @resource_name   = options[:resource_name]
       @only            = options[:only] ? Array(options[:only]) : nil
       @except          = options[:except] ? Array(options[:except]) : nil
+      @namespace       = options[:namespace]
       @key_format      = options[:key_format] || options[:each_serializer].try(:key_format)
     end
     attr_accessor :object, :scope, :root, :meta_key, :meta, :key_format
@@ -33,13 +34,13 @@ module ActiveModel
     end
 
     def serializer_for(item)
-      serializer_class = @each_serializer || Serializer.serializer_for(item) || DefaultSerializer
+      serializer_class = @each_serializer || Serializer.serializer_for(item, namespace: @namespace) || DefaultSerializer
       serializer_class.new(item, scope: scope, key_format: key_format, only: @only, except: @except, polymorphic: @polymorphic)
     end
 
     def serializable_object
       @object.map do |item|
-        serializer_for(item).serializable_object
+        serializer_for(item).serializable_object_with_notification
       end
     end
     alias_method :serializable_array, :serializable_object
@@ -59,6 +60,7 @@ module ActiveModel
     end
 
     private
+
     def instrumentation_keys
       [:object, :scope, :root, :meta_key, :meta, :each_serializer, :resource_name, :key_format]
     end
diff --git a/lib/active_model/serializable.rb b/lib/active_model/serializable.rb
index e70a9afc..9a33d397 100644
--- a/lib/active_model/serializable.rb
+++ b/lib/active_model/serializable.rb
@@ -1,5 +1,11 @@
+require 'active_model/serializable/utils'
+
 module ActiveModel
   module Serializable
+    def self.included(base)
+      base.extend Utils
+    end
+
     def as_json(options={})
       instrument('!serialize') do
         if root = options.fetch(:root, json_key)
@@ -12,6 +18,12 @@ module ActiveModel
       end
     end
 
+    def serializable_object_with_notification
+      instrument('!serialize') do
+        serializable_object
+      end
+    end
+
     def serializable_data
       embedded_in_root_associations.tap do |hash|
         if respond_to?(:meta) && meta
@@ -20,11 +32,21 @@ module ActiveModel
       end
     end
 
+    def namespace
+      get_namespace && Utils._const_get(get_namespace)
+    end
+
     def embedded_in_root_associations
       {}
     end
 
     private
+
+    def get_namespace
+      modules = self.class.name.split('::')
+      modules[0..-2].join('::') if modules.size > 1
+    end
+
     def instrument(action, &block)
       payload = instrumentation_keys.inject({ serializer: self.class.name }) do |payload, key|
         payload[:payload] = self.instance_variable_get(:"@#{key}")
diff --git a/lib/active_model/serializable/utils.rb b/lib/active_model/serializable/utils.rb
new file mode 100644
index 00000000..7471bd0f
--- /dev/null
+++ b/lib/active_model/serializable/utils.rb
@@ -0,0 +1,12 @@
+module ActiveModel
+  module Serializable
+    module Utils
+      extend self
+
+      def _const_get(const)
+        method = RUBY_VERSION >= '2.0' ? :const_get : :qualified_const_get
+        Object.send method, const
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index bb7ef131..689e132a 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -55,32 +55,18 @@ end
       end
       attr_reader :key_format
 
-      if RUBY_VERSION >= '2.0'
-        def serializer_for(resource)
-          if resource.respond_to?(:to_ary)
-            if Object.constants.include?(:ArraySerializer)
-              ::ArraySerializer
-            else
-              ArraySerializer
-            end
+      def serializer_for(resource, options = {})
+        if resource.respond_to?(:to_ary)
+          if Object.constants.include?(:ArraySerializer)
+            ::ArraySerializer
           else
-            begin
-              Object.const_get "#{resource.class.name}Serializer"
-            rescue NameError
-              nil
-            end
+            ArraySerializer
           end
-        end
-      else
-        def serializer_for(resource)
-          if resource.respond_to?(:to_ary)
-            if Object.constants.include?(:ArraySerializer)
-              ::ArraySerializer
-            else
-              ArraySerializer
-            end
-          else
-            "#{resource.class.name}Serializer".safe_constantize
+        else
+          begin
+            _const_get build_serializer_class(resource, options)
+          rescue NameError
+            nil
           end
         end
       end
@@ -113,6 +99,14 @@ end
 
       private
 
+      def build_serializer_class(resource, options)
+        "".tap do |klass_name|
+          klass_name << "#{options[:namespace]}::" if options[:namespace]
+          klass_name << options[:prefix].to_s.classify if options[:prefix]
+          klass_name << "#{resource.class.name}Serializer"
+        end
+      end
+
       def associate(klass, *attrs)
         options = attrs.extract_options!
 
@@ -219,7 +213,16 @@ end
 
     def build_serializer(association)
       object = send(association.name)
-      association.build_serializer(object, scope: scope)
+      association.build_serializer(object, association_options_for_serializer(association))
+    end
+
+    def association_options_for_serializer(association)
+      prefix = association.options[:prefix]
+
+      { scope: scope }.tap do |opts|
+        opts[:namespace] = namespace if namespace
+        opts[:prefix]    = prefix    if prefix
+      end
     end
 
     def serialize(association)
diff --git a/lib/active_model/serializer/association.rb b/lib/active_model/serializer/association.rb
index f62c982f..5ea22056 100644
--- a/lib/active_model/serializer/association.rb
+++ b/lib/active_model/serializer/association.rb
@@ -42,8 +42,8 @@ module ActiveModel
         @embed_objects = embed == :object || embed == :objects
       end
 
-      def serializer_from_object(object)
-        Serializer.serializer_for(object)
+      def serializer_from_object(object, options = {})
+        Serializer.serializer_for(object, options)
       end
 
       def default_serializer
@@ -51,7 +51,7 @@ module ActiveModel
       end
 
       def build_serializer(object, options = {})
-        serializer_class(object).new(object, options.merge(self.options))
+        serializer_class(object, options).new(object, options.merge(self.options))
       end
     end
   end
diff --git a/lib/active_model/serializer/association/has_many.rb b/lib/active_model/serializer/association/has_many.rb
index 4480afc6..d1b8d8eb 100644
--- a/lib/active_model/serializer/association/has_many.rb
+++ b/lib/active_model/serializer/association/has_many.rb
@@ -8,7 +8,7 @@ module ActiveModel
           @key ||= "#{name.to_s.singularize}_ids"
         end
 
-        def serializer_class(object)
+        def serializer_class(object, _)
           if use_array_serializer?
             ArraySerializer
           else
diff --git a/lib/active_model/serializer/association/has_one.rb b/lib/active_model/serializer/association/has_one.rb
index 4965e428..3b9acddf 100644
--- a/lib/active_model/serializer/association/has_one.rb
+++ b/lib/active_model/serializer/association/has_one.rb
@@ -8,8 +8,8 @@ module ActiveModel
           @key ||= "#{name}_id"
         end
 
-        def serializer_class(object)
-          serializer_from_options || serializer_from_object(object) || default_serializer
+        def serializer_class(object, options = {})
+          serializer_from_options || serializer_from_object(object, options) || default_serializer
         end
 
         def build_serializer(object, options = {})
diff --git a/test/fixtures/poro.rb b/test/fixtures/poro.rb
index 17011ba7..14fa3e5a 100644
--- a/test/fixtures/poro.rb
+++ b/test/fixtures/poro.rb
@@ -135,3 +135,10 @@ end
 class VideoSerializer < ActiveModel::Serializer
   attributes :html
 end
+
+class ShortProfileSerializer < ::ProfileSerializer; end
+
+module TestNamespace
+  class ProfileSerializer < ::ProfileSerializer; end
+  class UserSerializer    < ::UserSerializer;    end
+end
diff --git a/test/integration/action_controller/namespaced_serialization_test.rb b/test/integration/action_controller/namespaced_serialization_test.rb
new file mode 100644
index 00000000..4a5fbbf9
--- /dev/null
+++ b/test/integration/action_controller/namespaced_serialization_test.rb
@@ -0,0 +1,47 @@
+require 'test_helper'
+
+module ActionController
+  module Serialization
+    class NamespacedSerializationTest < ActionController::TestCase
+      class TestNamespace::MyController < ActionController::Base
+        def render_profile_with_namespace
+          render json: Profile.new({ name: 'Name 1', description: 'Description 1'})
+        end
+
+        def render_profiles_with_namespace
+          render json: [Profile.new({ name: 'Name 1', description: 'Description 1'})]
+        end
+
+        def render_comment
+          render json: Comment.new(content: 'Comment 1')
+        end
+
+        def render_comments
+          render json: [Comment.new(content: 'Comment 1')]
+        end
+      end
+
+      tests TestNamespace::MyController
+
+      def test_render_profile_with_namespace
+        get :render_profile_with_namespace
+        assert_serializer TestNamespace::ProfileSerializer
+      end
+
+      def test_render_profiles_with_namespace
+        get :render_profiles_with_namespace
+        assert_serializer TestNamespace::ProfileSerializer
+      end
+
+      def test_fallback_to_a_version_without_namespace
+        get :render_comment
+        assert_serializer CommentSerializer
+      end
+
+      def test_array_fallback_to_a_version_without_namespace
+        get :render_comments
+        assert_serializer CommentSerializer
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/test/unit/active_model/serializer/associations/build_serializer_test.rb b/test/unit/active_model/serializer/associations/build_serializer_test.rb
index 2848badf..414a400f 100644
--- a/test/unit/active_model/serializer/associations/build_serializer_test.rb
+++ b/test/unit/active_model/serializer/associations/build_serializer_test.rb
@@ -7,6 +7,7 @@ module ActiveModel
         def setup
           @association = Association::HasOne.new('post', serializer: PostSerializer)
           @post = Post.new({ title: 'Title 1', body: 'Body 1', date: '1/1/2000' })
+          @user = User.new
         end
 
         def test_build_serializer_for_array_called_twice
@@ -15,6 +16,20 @@ module ActiveModel
             assert_instance_of(PostSerializer, serializer)
           end
         end
+
+        def test_build_serializer_from_in_a_namespace
+          assoc      = Association::HasOne.new('profile')
+          serializer = TestNamespace::UserSerializer.new(@user).build_serializer(assoc)
+
+          assert_instance_of(TestNamespace::ProfileSerializer, serializer)
+        end
+
+        def test_build_serializer_with_prefix
+          assoc      = Association::HasOne.new('profile', prefix: :short)
+          serializer = UserSerializer.new(@user).build_serializer(assoc)
+
+          assert_instance_of(ShortProfileSerializer, serializer)
+        end
       end
     end
   end