diff --git a/README.rdoc b/README.rdoc
index bbbfe927..a0c5317c 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -1018,6 +1018,24 @@ try {rack-cache}[http://rtomayko.github.com/rack-cache/]:
 Use the <tt>:static_cache_control</tt> setting (see below) to add
 <tt>Cache-Control</tt> header info to static files.
 
+According to RFC 2616 your application should behave differently if the
+If-Matches of If-None-Matches header is set to <tt>*</tt> depending on whether
+the resource requested is already in existence. Sinatra assumes resources for
+safe (like get) and idempotent (like put) requests are already in existence,
+whereas other resources (for instance for post requests), are treated as new
+resources. You can change this behavior by passing in a <tt>:new_resource</tt>
+option:
+
+  get '/create' do
+    etag '', :new_resource => true
+    Article.create
+    erb :new_article
+  end
+
+If you still want to use a weak ETag, pass in a <tt>:kind</tt> option:
+
+  etag '', :new_resource => true, :kind => :weak
+
 === Sending Files
 
 For sending files, you can use the <tt>send_file</tt> helper method:
diff --git a/lib/sinatra/base.rb b/lib/sinatra/base.rb
index df51d3d3..cf5a432b 100644
--- a/lib/sinatra/base.rb
+++ b/lib/sinatra/base.rb
@@ -355,8 +355,12 @@ module Sinatra
       return unless time
       time = time_for time
       response['Last-Modified'] = time.httpdate
-      # compare based on seconds since epoch
-      halt 304 if Time.httpdate(env['HTTP_IF_MODIFIED_SINCE']).to_i >= time.to_i
+
+      unless env['HTTP_IF_NONE_MATCH']
+        # compare based on seconds since epoch
+        since = Time.httpdate(env['HTTP_IF_MODIFIED_SINCE']).to_i
+        halt 304 if since >= time.to_i
+      end
     rescue ArgumentError
     end
 
@@ -369,22 +373,36 @@ module Sinatra
     # When the current request includes an 'If-None-Match' header with a
     # matching etag, execution is immediately halted. If the request method is
     # GET or HEAD, a '304 Not Modified' response is sent.
-    def etag(value, kind = :strong)
-      raise ArgumentError, ":strong or :weak expected" unless [:strong,:weak].include?(kind)
+    def etag(value, options = {})
+      # Before touching this code, please double check RFC 2616 14.24 and 14.26.
+      options      = {:kind => options} unless Hash === options
+      kind         = options[:kind] || :strong
+      new_resource = options.fetch(:new_resource) { request.post? }
+
+      unless [:strong, :weak].include?(kind)
+        raise ArgumentError, ":strong or :weak expected"
+      end
+
       value = '"%s"' % value
       value = 'W/' + value if kind == :weak
       response['ETag'] = value
 
-      if etags = env['HTTP_IF_NONE_MATCH']
-        etags = etags.split(/\s*,\s*/)
-        if etags.include?(value) or etags.include?('*')
-          halt 304 if request.safe?
-        else
-          halt 412 unless request.safe?
+      if success? or status == 304
+        if etag_matches? env['HTTP_IF_NONE_MATCH'], new_resource
+          halt(request.safe? ? 304 : 412)
+        end
+
+        if env['HTTP_IF_MATCH']
+          halt 412 unless etag_matches? env['HTTP_IF_MATCH'], new_resource
         end
       end
     end
 
+    def etag_matches?(list, new_resource = request.post?)
+      return !new_resource if list == '*'
+      list.to_s.split(/\s*,\s*/).include? response['ETag']
+    end
+
     # Sugar for redirect (example:  redirect back)
     def back
       request.referer
diff --git a/test/helper.rb b/test/helper.rb
index 972b416b..1f061d49 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -72,6 +72,10 @@ class Test::Unit::TestCase
     assert_equal value.lstrip.gsub(/\s*\n\s*/, ""), body.lstrip.gsub(/\s*\n\s*/, "")
   end
 
+  def assert_status(expected)
+    assert_equal Integer(expected), Integer(status)
+  end
+
   def assert_like(a,b)
     pattern = /id=['"][^"']*["']|\s+/
     assert_equal a.strip.gsub(pattern, ""), b.strip.gsub(pattern, "")
diff --git a/test/helpers_test.rb b/test/helpers_test.rb
index ca6d1c82..46055dda 100644
--- a/test/helpers_test.rb
+++ b/test/helpers_test.rb
@@ -960,69 +960,622 @@ class HelpersTest < Test::Unit::TestCase
   end
 
   describe 'etag' do
-    setup do
-      mock_app {
-        get '/' do
-          body { 'Hello World' }
-          etag 'FOO'
-          'Boo!'
+    context "safe requests" do
+      it 'returns 200 for normal requests' do
+        mock_app do
+          get '/' do
+            etag 'foo'
+            'ok'
+          end
         end
 
-        post '/' do
-          etag 'FOO'
-          'Matches!'
+        get('/')
+        assert_status 200
+        assert_body 'ok'
+      end
+
+      context "If-None-Match" do
+        it 'returns 304 when If-None-Match is *' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 304
+          assert_body ''
         end
-      }
+
+        it 'returns 200 when If-None-Match is * for new resources' do
+          mock_app do
+            get '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 304 when If-None-Match is * for existing resources' do
+          mock_app do
+            get '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 304
+          assert_body ''
+        end
+
+        it 'returns 304 when If-None-Match is the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 304
+          assert_body ''
+        end
+
+        it 'returns 304 when If-None-Match includes the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar", "foo"')
+          assert_status 304
+          assert_body ''
+        end
+
+        it 'returns 200 when If-None-Match does not include the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'ignores If-Modified-Since if If-None-Match does not match' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              last_modified Time.at(0)
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'does not change a status code other than 2xx or 304' do
+          mock_app do
+            get '/' do
+              status 499
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 499
+          assert_body 'ok'
+        end
+
+        it 'does change 2xx status codes' do
+          mock_app do
+            get '/' do
+              status 299
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 304
+          assert_body ''
+        end
+
+        it 'does not send a body on 304 status codes' do
+          mock_app do
+            get '/' do
+              status 304
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 304
+          assert_body ''
+        end
+      end
+
+      context "If-Match" do
+        it 'returns 200 when If-Match is the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '"foo"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 200 when If-Match includes the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '"foo", "bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 200 when If-Match is *' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match is * for new resources' do
+          mock_app do
+            get '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-Match is * for existing resources' do
+          mock_app do
+            get '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match does not include the etag' do
+          mock_app do
+            get '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          get('/', {}, 'HTTP_IF_MATCH' => '"bar"')
+          assert_status 412
+          assert_body ''
+        end
+      end
     end
 
-    it 'sets the ETag header' do
-      get '/'
-      assert_equal '"FOO"', response['ETag']
+    context "idempotent requests" do
+      it 'returns 200 for normal requests' do
+        mock_app do
+          put '/' do
+            etag 'foo'
+            'ok'
+          end
+        end
+
+        put('/')
+        assert_status 200
+        assert_body 'ok'
+      end
+
+      context "If-None-Match" do
+        it 'returns 412 when If-None-Match is *' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-None-Match is * for new resources' do
+          mock_app do
+            put '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-None-Match is * for existing resources' do
+          mock_app do
+            put '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 412 when If-None-Match is the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 412 when If-None-Match includes the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar", "foo"')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-None-Match does not include the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'ignores If-Modified-Since if If-None-Match does not match' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              last_modified Time.at(0)
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+      end
+
+      context "If-Match" do
+        it 'returns 200 when If-Match is the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '"foo"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 200 when If-Match includes the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '"foo", "bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 200 when If-Match is *' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match is * for new resources' do
+          mock_app do
+            put '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-Match is * for existing resources' do
+          mock_app do
+            put '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match does not include the etag' do
+          mock_app do
+            put '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          put('/', {}, 'HTTP_IF_MATCH' => '"bar"')
+          assert_status 412
+          assert_body ''
+        end
+      end
     end
 
-    it 'returns a body when conditional get misses' do
-      get '/'
-      assert_equal 200, status
-      assert_equal 'Boo!', body
-    end
+    context "post requests" do
+      it 'returns 200 for normal requests' do
+        mock_app do
+          post '/' do
+            etag 'foo'
+            'ok'
+          end
+        end
 
-    it 'returns a body when posting with no If-None-Match header' do
-      post '/'
-      assert_equal 200, status
-      assert_equal 'Matches!', body
-    end
+        post('/')
+        assert_status 200
+        assert_body 'ok'
+      end
 
-    it 'returns a body when conditional post matches' do
-      post '/', {}, { 'HTTP_IF_NONE_MATCH' => '"FOO"' }
-      assert_equal 200, status
-      assert_equal 'Matches!', body
-    end
+      context "If-None-Match" do
+        it 'returns 200 when If-None-Match is *' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
 
-    it 'halts with 412 when conditional post misses' do
-      post '/', {}, { 'HTTP_IF_NONE_MATCH' => '"BAR"' }
-      assert_equal 412, status
-      assert_equal '', body
-    end
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
 
-    it 'halts when a conditional GET matches' do
-      get '/', {}, { 'HTTP_IF_NONE_MATCH' => '"FOO"' }
-      assert_equal 304, status
-      assert_equal '', body
-    end
+        it 'returns 200 when If-None-Match is * for new resources' do
+          mock_app do
+            post '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
 
-    it 'should handle multiple ETag values in If-None-Match header' do
-      get '/', {}, { 'HTTP_IF_NONE_MATCH' => '"BAR", *' }
-      assert_equal 304, status
-      assert_equal '', body
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-None-Match is * for existing resources' do
+          mock_app do
+            post '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 412 when If-None-Match is the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '"foo"')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 412 when If-None-Match includes the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar", "foo"')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-None-Match does not include the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'ignores If-Modified-Since if If-None-Match does not match' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              last_modified Time.at(0)
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_NONE_MATCH' => '"bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+      end
+
+      context "If-Match" do
+        it 'returns 200 when If-Match is the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '"foo"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 200 when If-Match includes the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '"foo", "bar"')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match is *' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 412 when If-Match is * for new resources' do
+          mock_app do
+            post '/' do
+              etag 'foo', :new_resource => true
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 412
+          assert_body ''
+        end
+
+        it 'returns 200 when If-Match is * for existing resources' do
+          mock_app do
+            post '/' do
+              etag 'foo', :new_resource => false
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '*')
+          assert_status 200
+          assert_body 'ok'
+        end
+
+        it 'returns 412 when If-Match does not include the etag' do
+          mock_app do
+            post '/' do
+              etag 'foo'
+              'ok'
+            end
+          end
+
+          post('/', {}, 'HTTP_IF_MATCH' => '"bar"')
+          assert_status 412
+          assert_body ''
+        end
+      end
     end
 
     it 'uses a weak etag with the :weak option' do
-      mock_app {
+      mock_app do
         get '/' do
           etag 'FOO', :weak
           "that's weak, dude."
         end
-      }
+      end
       get '/'
       assert_equal 'W/"FOO"', response['ETag']
     end