diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index ba484a17cf..cc6c692af6 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -10,6 +10,8 @@
 
 * Fix more obscure nested parameter hash parsing bug.  #10797 [thomas.lee]
 
+* Added ActionView::Helpers::register_javascript/stylesheet_expansion to make it easier for plugin developers to inject multiple assets.  #10350 [lotswholetime]
+
 * Fix nested parameter hash parsing bug.  #10797 [thomas.lee]
 
 * Allow using named routes in ActionController::TestCase before any request has been made. Closes #11273 [alloy]
diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 2939dfbbef..d57d1e0903 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -155,7 +155,8 @@ module ActionView
       alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with a javascript_path named route
 
       JAVASCRIPT_DEFAULT_SOURCES = ['prototype', 'effects', 'dragdrop', 'controls'] unless const_defined?(:JAVASCRIPT_DEFAULT_SOURCES)
-      @@javascript_default_sources = JAVASCRIPT_DEFAULT_SOURCES.dup
+      @@javascript_expansions = { :defaults => JAVASCRIPT_DEFAULT_SOURCES.dup }
+      @@stylesheet_expansions = {}
 
       # Returns an html script tag for each of the +sources+ provided. You
       # can pass in the filename (.js extension is optional) of javascript files
@@ -249,16 +250,46 @@ module ActionView
         end
       end
 
+      # Register one or more javascript files to be included when <tt>symbol</tt>
+      # is passed to <tt>javascript_include_tag</tt>. This method is typically intended
+      # to be called from plugin initialization to register javascript files
+      # that the plugin installed in <tt>public/javascripts</tt>.
+      #
+      #   ActionView::Helpers::AssetTagHelper.register_javascript_expansion :monkey => ["head", "body", "tail"]
+      #
+      #   javascript_include_tag :monkey # =>
+      #     <script type="text/javascript" src="/javascripts/head.js"></script>
+      #     <script type="text/javascript" src="/javascripts/body.js"></script>
+      #     <script type="text/javascript" src="/javascripts/tail.js"></script>
+      def self.register_javascript_expansion(expansions)
+        @@javascript_expansions.merge!(expansions)
+      end
+
+      # Register one or more stylesheet files to be included when <tt>symbol</tt>
+      # is passed to <tt>stylesheet_link_tag</tt>. This method is typically intended
+      # to be called from plugin initialization to register stylesheet files
+      # that the plugin installed in <tt>public/stylesheets</tt>.
+      #
+      #   ActionView::Helpers::AssetTagHelper.register_stylesheet_expansion :monkey => ["head", "body", "tail"]
+      #
+      #   stylesheet_link_tag :monkey # =>
+      #     <link href="/stylesheets/head.css"  media="screen" rel="stylesheet" type="text/css" />
+      #     <link href="/stylesheets/body.css"  media="screen" rel="stylesheet" type="text/css" />
+      #     <link href="/stylesheets/tail.css"  media="screen" rel="stylesheet" type="text/css" />
+      def self.register_stylesheet_expansion(expansions)
+        @@stylesheet_expansions.merge!(expansions)
+      end
+
       # Register one or more additional JavaScript files to be included when
       # <tt>javascript_include_tag :defaults</tt> is called. This method is
       # typically intended to be called from plugin initialization to register additional
       # .js files that the plugin installed in <tt>public/javascripts</tt>.
       def self.register_javascript_include_default(*sources)
-        @@javascript_default_sources.concat(sources)
+        @@javascript_expansions[:defaults].concat(sources)
       end
 
       def self.reset_javascript_include_default #:nodoc:
-        @@javascript_default_sources = JAVASCRIPT_DEFAULT_SOURCES.dup
+        @@javascript_expansions[:defaults] = JAVASCRIPT_DEFAULT_SOURCES.dup
       end
 
       # Computes the path to a stylesheet asset in the public stylesheets directory.
@@ -534,28 +565,34 @@ module ActionView
         end
 
         def expand_javascript_sources(sources)
-          case
-          when sources.include?(:all)
+          if sources.include?(:all)
             all_javascript_files = Dir[File.join(JAVASCRIPTS_DIR, '*.js')].collect { |file| File.basename(file).split(".", 0).first }.sort
-            sources = ((@@javascript_default_sources.dup & all_javascript_files) + all_javascript_files).uniq
-
-          when sources.include?(:defaults)
-            sources = sources[0..(sources.index(:defaults))] + 
-              @@javascript_default_sources.dup + 
-              sources[(sources.index(:defaults) + 1)..sources.length]
-
-            sources.delete(:defaults)
-            sources << "application" if file_exist?(File.join(JAVASCRIPTS_DIR, "application.js"))
+            @@all_javascript_sources ||= ((determine_source(:defaults, @@javascript_expansions).dup & all_javascript_files) + all_javascript_files).uniq
+          else
+            expanded_sources = sources.collect do |source|
+              determine_source(source, @@javascript_expansions)
+            end.flatten
+            expanded_sources << "application" if sources.include?(:defaults) && file_exist?(File.join(JAVASCRIPTS_DIR, "application.js"))
+            expanded_sources
           end
-
-          sources
         end
 
         def expand_stylesheet_sources(sources)
           if sources.first == :all
-            @@all_stylesheet_sources ||= Dir[File.join(STYLESHEETS_DIR, '*.css')].collect { |file| File.basename(file).split(".", 1).first }.sort
+            @@all_stylesheet_sources ||= Dir[File.join(STYLESHEETS_DIR, '*.css')].collect { |file| File.basename(file).split(".", 0).first }.sort
           else
-            sources
+            sources.collect do |source|
+              determine_source(source, @@stylesheet_expansions)
+            end.flatten
+          end
+        end
+
+        def determine_source(source, collection)
+          case source
+          when Symbol
+            collection[source] || raise(ArgumentError, "No expansion found for #{source.inspect}")
+          else
+            source
           end
         end
 
diff --git a/actionpack/test/fixtures/public/javascripts/application.js b/actionpack/test/fixtures/public/javascripts/application.js
index e69de29bb2..9702692980 100644
--- a/actionpack/test/fixtures/public/javascripts/application.js
+++ b/actionpack/test/fixtures/public/javascripts/application.js
@@ -0,0 +1 @@
+// application js
\ No newline at end of file
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index ffd1d955e1..be605329fc 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -84,7 +84,7 @@ class AssetTagHelperTest < Test::Unit::TestCase
     %(javascript_include_tag("xmlhr", :lang => "vbscript")) => %(<script lang="vbscript" src="/javascripts/xmlhr.js" type="text/javascript"></script>),
     %(javascript_include_tag("common.javascript", "/elsewhere/cools")) => %(<script src="/javascripts/common.javascript" type="text/javascript"></script>\n<script src="/elsewhere/cools.js" type="text/javascript"></script>),
     %(javascript_include_tag(:defaults)) => %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>),
-    %(javascript_include_tag(:all)) => %(<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
+    %(javascript_include_tag(:all)) => %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
     %(javascript_include_tag(:defaults, "test")) => %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/test.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>),
     %(javascript_include_tag("test", :defaults)) => %(<script src="/javascripts/test.js" type="text/javascript"></script>\n<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>)
   }
@@ -175,6 +175,22 @@ class AssetTagHelperTest < Test::Unit::TestCase
     assert_dom_equal  %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/slider.js" type="text/javascript"></script>\n<script src="/javascripts/lib1.js" type="text/javascript"></script>\n<script src="/elsewhere/blub/lib2.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>), javascript_include_tag(:defaults)
   end
   
+  def test_custom_javascript_expansions
+    ActionView::Helpers::AssetTagHelper::register_javascript_expansion :monkey => ["head", "body", "tail"]
+    assert_dom_equal  %(<script src="/javascripts/first.js" type="text/javascript"></script>\n<script src="/javascripts/head.js" type="text/javascript"></script>\n<script src="/javascripts/body.js" type="text/javascript"></script>\n<script src="/javascripts/tail.js" type="text/javascript"></script>\n<script src="/javascripts/last.js" type="text/javascript"></script>), javascript_include_tag('first', :monkey, 'last')
+  end
+
+  def test_custom_javascript_expansions_and_defaults_puts_application_js_at_the_end
+    ENV["RAILS_ASSET_ID"] = ""
+    ActionView::Helpers::AssetTagHelper::register_javascript_expansion :monkey => ["head", "body", "tail"]
+    assert_dom_equal  %(<script src="/javascripts/first.js" type="text/javascript"></script>\n<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/head.js" type="text/javascript"></script>\n<script src="/javascripts/body.js" type="text/javascript"></script>\n<script src="/javascripts/tail.js" type="text/javascript"></script>\n<script src="/javascripts/last.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>), javascript_include_tag('first', :defaults, :monkey, 'last')
+  end
+
+  def test_custom_javascript_expansions_with_undefined_symbol
+    ActionView::Helpers::AssetTagHelper::register_javascript_expansion :monkey => nil
+    assert_raise(ArgumentError) { javascript_include_tag('first', :monkey, 'last') }
+  end
+
   def test_stylesheet_path
     StylePathToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end
@@ -188,6 +204,16 @@ class AssetTagHelperTest < Test::Unit::TestCase
     StyleLinkToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end
 
+  def test_custom_stylesheet_expansions
+    ActionView::Helpers::AssetTagHelper::register_stylesheet_expansion :monkey => ["head", "body", "tail"]
+    assert_dom_equal  %(<link href="/stylesheets/first.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/head.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/body.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/tail.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/last.css" media="screen" rel="stylesheet" type="text/css" />), stylesheet_link_tag('first', :monkey, 'last')
+  end
+
+  def test_custom_stylesheet_expansions_with_undefined_symbol
+    ActionView::Helpers::AssetTagHelper::register_stylesheet_expansion :monkey => nil
+    assert_raise(ArgumentError) { stylesheet_link_tag('first', :monkey, 'last') }
+  end
+
   def test_image_path
     ImagePathToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end
@@ -319,19 +345,40 @@ class AssetTagHelperTest < Test::Unit::TestCase
     FileUtils.rm_f(File.join(ActionView::Helpers::AssetTagHelper::JAVASCRIPTS_DIR, 'cache', 'money.js'))
   end
   
+  def test_caching_javascript_include_tag_with_all_puts_defaults_at_the_start_of_the_file
+    ENV["RAILS_ASSET_ID"] = ""
+    ActionController::Base.asset_host = 'http://a0.example.com'
+    ActionController::Base.perform_caching = true
+
+    assert_dom_equal(
+      %(<script src="http://a0.example.com/javascripts/combined.js" type="text/javascript"></script>),
+      javascript_include_tag(:all, :cache => "combined")
+    )
+
+    assert File.exist?(File.join(ActionView::Helpers::AssetTagHelper::JAVASCRIPTS_DIR, 'combined.js'))
+
+    assert_equal(
+      %(// prototype js\n\n// effects js\n\n// dragdrop js\n\n// controls js\n\n// application js\n\n// bank js\n\n// robber js),
+      IO.read(File.join(ActionView::Helpers::AssetTagHelper::JAVASCRIPTS_DIR, 'combined.js'))
+    )
+
+  ensure
+    FileUtils.rm_f(File.join(ActionView::Helpers::AssetTagHelper::JAVASCRIPTS_DIR, 'combined.js'))
+  end
+
   def test_caching_javascript_include_tag_when_caching_off
     ENV["RAILS_ASSET_ID"] = ""
     ActionController::Base.perform_caching = false
     
     assert_dom_equal(
-      %(<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
+      %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
       javascript_include_tag(:all, :cache => true)
     )
 
     assert !File.exist?(File.join(ActionView::Helpers::AssetTagHelper::JAVASCRIPTS_DIR, 'all.js'))
     
     assert_dom_equal(
-      %(<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
+      %(<script src="/javascripts/prototype.js" type="text/javascript"></script>\n<script src="/javascripts/effects.js" type="text/javascript"></script>\n<script src="/javascripts/dragdrop.js" type="text/javascript"></script>\n<script src="/javascripts/controls.js" type="text/javascript"></script>\n<script src="/javascripts/application.js" type="text/javascript"></script>\n<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>),
       javascript_include_tag(:all, :cache => "money")
     )