diff --git a/README.md b/README.md
index 199edefa..9a9a850a 100644
--- a/README.md
+++ b/README.md
@@ -386,7 +386,7 @@ Now, any associations will be supplied as an Array of IDs:
     "id": 1,
     "title": "New post",
     "body": "A body!",
-    "comments": [ 1, 2, 3 ]
+    "comment_ids": [ 1, 2, 3 ]
   }
 }
 ```
@@ -413,7 +413,7 @@ The JSON will look like this:
     "comments": [
       { "id": 1, "body": "what a dumb post" }
     ],
-    "tags": [ 1, 2, 3 ]
+    "tag_ids": [ 1, 2, 3 ]
   }
 }
 ```
@@ -444,11 +444,11 @@ this:
     "id": 1,
     "title": "New post",
     "body": "A body!",
-    "comments": [ 1, 2 ]
+    "comment_ids": [ 1, 2 ]
   },
   "comments": [
-    { "id": 1, "body": "what a dumb post", "tags": [ 1, 2 ] },
-    { "id": 2, "body": "i liked it", "tags": [ 1, 3 ] },
+    { "id": 1, "body": "what a dumb post", "tag_ids": [ 1, 2 ] },
+    { "id": 2, "body": "i liked it", "tag_ids": [ 1, 3 ] },
   ],
   "tags": [
     { "id": 1, "name": "short" },
diff --git a/lib/active_model/serializer/associations.rb b/lib/active_model/serializer/associations.rb
index 0e06c698..66478706 100644
--- a/lib/active_model/serializer/associations.rb
+++ b/lib/active_model/serializer/associations.rb
@@ -51,7 +51,7 @@ module ActiveModel
         end
 
         def root
-          option(:root) || plural_key
+          option(:root) || @name
         end
 
         def name
@@ -92,7 +92,15 @@ module ActiveModel
       end
 
       class HasMany < Config #:nodoc:
-        alias plural_key key
+        def key
+          if key = option(:key)
+            key
+          elsif embed_ids?
+            "#{@name.to_s.singularize}_ids".to_sym
+          else
+            @name
+          end
+        end
 
         def serialize
           associated_object.map do |item|
@@ -132,18 +140,30 @@ module ActiveModel
           option :polymorphic
         end
 
-        def polymorphic_key
-          associated_object.class.to_s.demodulize.underscore.to_sym
-        end
-
-        def plural_key
-          if polymorphic?
+        def root
+          if root = option(:root)
+            root
+          elsif polymorphic?
             associated_object.class.to_s.pluralize.demodulize.underscore.to_sym
           else
-            key.to_s.pluralize.to_sym
+            @name.to_s.pluralize.to_sym
           end
         end
 
+        def key
+          if key = option(:key)
+            key
+          elsif embed_ids? && !polymorphic?
+            "#{@name}_id".to_sym
+          else
+            @name
+          end
+        end
+
+        def polymorphic_key
+          associated_object.class.to_s.demodulize.underscore.to_sym
+        end
+
         def serialize
           object = associated_object
 
diff --git a/test/association_test.rb b/test/association_test.rb
index f766b5ab..349a374c 100644
--- a/test/association_test.rb
+++ b/test/association_test.rb
@@ -70,7 +70,7 @@ class AssociationTest < ActiveModel::TestCase
       include! :comments, :value => @post.comments
 
       assert_equal({
-        :comments => [ 1 ]
+        :comment_ids => [ 1 ]
       }, @hash)
 
       assert_equal({
@@ -91,7 +91,7 @@ class AssociationTest < ActiveModel::TestCase
       include! :comments, :value => @post.comments, :embed => :ids, :include => false
 
       assert_equal({
-        :comments => [ 1 ]
+        :comment_ids => [ 1 ]
       }, @hash)
 
       assert_equal({}, @root_hash)
@@ -101,7 +101,7 @@ class AssociationTest < ActiveModel::TestCase
       include! :comment, :value => @post.comment
 
       assert_equal({
-        :comment => 1
+        :comment_id => 1
       }, @hash)
 
       assert_equal({
@@ -119,7 +119,7 @@ class AssociationTest < ActiveModel::TestCase
       include! :comments
 
       assert_equal({
-        :comments => [ 1 ]
+        :comment_ids => [ 1 ]
       }, @hash)
 
       assert_equal({
@@ -137,7 +137,7 @@ class AssociationTest < ActiveModel::TestCase
       include! :comment
 
       assert_equal({
-        :comment => 1
+        :comment_id => 1
       }, @hash)
 
       assert_equal({
@@ -159,7 +159,7 @@ class AssociationTest < ActiveModel::TestCase
       }, @hash)
 
       assert_equal({
-        :custom_comments => [
+        :comments => [
           { :id => 1, :body => "ZOMG A COMMENT" }
         ]
       }, @root_hash)
@@ -167,17 +167,17 @@ class AssociationTest < ActiveModel::TestCase
 
     def test_with_default_has_one_with_custom_key
       @post_serializer_class.class_eval do
-        has_one :comment, :key => :custom_comment
+        has_one :comment, :key => :custom_comment_id
       end
 
       include! :comment
 
       assert_equal({
-        :custom_comment => 1
+        :custom_comment_id => 1
       }, @hash)
 
       assert_equal({
-        :custom_comments => [
+        :comments => [
           { :id => 1, :body => "ZOMG A COMMENT" }
         ]
       }, @root_hash)
@@ -207,7 +207,7 @@ class AssociationTest < ActiveModel::TestCase
       include_bare! :comments
 
       assert_equal({
-        :comments => [ 1 ]
+        :comment_ids => [ 1 ]
       }, @hash)
 
       assert_equal({}, @root_hash)
@@ -232,7 +232,7 @@ class AssociationTest < ActiveModel::TestCase
       include_bare! :comments
 
       assert_equal({
-        :comments => [ 1 ]
+        :comment_ids => [ 1 ]
       }, @hash)
 
       assert_equal({
@@ -250,7 +250,7 @@ class AssociationTest < ActiveModel::TestCase
       include_bare! :comment
 
       assert_equal({
-        :comment => 1
+        :comment_id => 1
       }, @hash)
 
       assert_equal({}, @root_hash)
@@ -275,7 +275,7 @@ class AssociationTest < ActiveModel::TestCase
       include_bare! :comment
 
       assert_equal({
-        :comment => 1
+        :comment_id => 1
       }, @hash)
 
       assert_equal({
@@ -333,7 +333,7 @@ class AssociationTest < ActiveModel::TestCase
         :post => {
           :title => "New Post",
           :body => "Body",
-          :comments => [ 1 ]
+          :comment_ids => [ 1 ]
         },
         :comments => [
           { :id => 1, :body => "ZOMG A COMMENT" }
@@ -352,7 +352,7 @@ class AssociationTest < ActiveModel::TestCase
         :post => {
           :title => "New Post",
           :body => "Body",
-          :comments => [ 1 ]
+          :comment_ids => [ 1 ]
         }
       }, json)
     end
@@ -368,7 +368,7 @@ class AssociationTest < ActiveModel::TestCase
         :post => {
           :title => "New Post",
           :body => "Body",
-          :comments => [ 1 ]
+          :comment_ids => [ 1 ]
         }
       }, json)
     end
@@ -384,7 +384,7 @@ class AssociationTest < ActiveModel::TestCase
         :post => {
           :title => "New Post",
           :body => "Body",
-          :comments => [ 1 ]
+          :comment_ids => [ 1 ]
         },
         :comments => [
           { :id => 1, :body => "ZOMG A COMMENT" }
diff --git a/test/serializer_test.rb b/test/serializer_test.rb
index 185b7c43..6be28ff8 100644
--- a/test/serializer_test.rb
+++ b/test/serializer_test.rb
@@ -281,8 +281,8 @@ class SerializerTest < ActiveModel::TestCase
       :post => {
         :title => "New Post",
         :body => "Body of new post",
-        :comments => [1, 2],
-        :author => nil
+        :comment_ids => [1, 2],
+        :author_id => nil
       }
     }, serializer.as_json)
   end
@@ -305,8 +305,8 @@ class SerializerTest < ActiveModel::TestCase
       :post => {
         :title => "New Post",
         :body => "Body of new post",
-        :comments => [1, 2],
-        :author => nil
+        :comment_ids => [1, 2],
+        :author_id => nil
       },
       :comments => [
         { :title => "Comment1" },
@@ -323,8 +323,8 @@ class SerializerTest < ActiveModel::TestCase
       :post => {
         :title => "New Post",
         :body => "Body of new post",
-        :comments => [1, 2],
-        :author => 1
+        :comment_ids => [1, 2],
+        :author_id => 1
       },
       :comments => [
         { :title => "Comment1" },
@@ -558,7 +558,7 @@ class SerializerTest < ActiveModel::TestCase
       :post => {
         :title => "New Post",
         :body => "It's a new post!",
-        :author => 5
+        :author_id => 5
       }
     }, hash.as_json)
   end
@@ -776,12 +776,12 @@ class SerializerTest < ActiveModel::TestCase
     actual = ActiveModel::ArraySerializer.new([post], :root => :posts).as_json
     assert_equal({
       :posts => [
-        { :title => "New Post", :body => "NEW POST", :id => 1, :comments => [1,2] }
+        { :title => "New Post", :body => "NEW POST", :id => 1, :comment_ids => [1,2] }
       ],
 
       :comments => [
-        { :body => "EWOT", :id => 1, :tags => [1,3] },
-        { :body => "YARLY", :id => 2, :tags => [1,2] }
+        { :body => "EWOT", :id => 1, :tag_ids => [1,3] },
+        { :body => "YARLY", :id => 2, :tag_ids => [1,2] }
       ],
 
       :tags => [