diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index 8acb585f91ed6..77bfec6e10b8a 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -375,7 +375,7 @@ def load_target
           target
         end
         
-        def method_missing(method, *args)
+        def method_missing(method, *args, &block)
           case method.to_s
           when 'find_or_create'
             return find(:first, :conditions => args.first) || create(args.first)
@@ -383,9 +383,9 @@ def method_missing(method, *args)
             rest = $1
             find_args = pull_finder_args_from(DynamicFinderMatch.match(method).attribute_names, *args)
             return  send("find_by_#{rest}", find_args) ||
-                    method_missing("create_by_#{rest}", *args)
+                    method_missing("create_by_#{rest}", *args, &block)
           when /^create_by_(.*)$/
-            return create($1.split('_and_').zip(args).inject({}) { |h,kv| k,v=kv ; h[k] = v ; h })
+            return create($1.split('_and_').zip(args).inject({}) { |h,kv| k,v=kv ; h[k] = v ; h }, &block)
           end
 
           if @target.respond_to?(method) || (!@reflection.klass.respond_to?(method) && Class.respond_to?(method))
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 0b1b579ff4a19..47b0f1e88d9ee 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -82,6 +82,12 @@ def test_find_or_create_by_with_additional_parameters
     assert_equal 4, post.comments.length
   end
 
+  def test_find_or_create_by_with_block
+    post = Post.create! :title => 'test_find_or_create_by_with_additional_parameters', :body => 'this is the body'
+    comment = post.comments.find_or_create_by_body('other test comment body') { |comment| comment.type = 'test' }
+    assert_equal 'test', comment.type
+  end
+
   def test_find_or_create
     person = Person.create! :first_name => 'tenderlove'
     post   = Post.find :first