diff --git a/actionpack/lib/action_view/helpers/date_helper.rb b/actionpack/lib/action_view/helpers/date_helper.rb
index 9806d51a87..c686982056 100755
--- a/actionpack/lib/action_view/helpers/date_helper.rb
+++ b/actionpack/lib/action_view/helpers/date_helper.rb
@@ -109,6 +109,9 @@ module ActionView
       #   date_select("credit_card", "bill_due", :default => { :day => 20 })
       #
       # The selects are prepared for multi-parameter assignment to an Active Record object.
+      #
+      # Note: If the day is not included as an option but the month is, the day will be set to the 1st to ensure that all month
+      # choices are valid.
       def date_select(object_name, method, options = {})
         InstanceTag.new(object_name, method, self, nil, options.delete(:object)).to_date_select_tag(options)
       end
@@ -122,6 +125,9 @@ module ActionView
       #   time_select("post", "start_time", :include_seconds => true)
       #
       # The selects are prepared for multi-parameter assignment to an Active Record object.
+      #
+      # Note: If the day is not included as an option but the month is, the day will be set to the 1st to ensure that all month
+      # choices are valid.
       def time_select(object_name, method, options = {})
         InstanceTag.new(object_name, method, self, nil, options.delete(:object)).to_time_select_tag(options)
       end
@@ -350,7 +356,7 @@ module ActionView
       include DateHelper
 
       def to_date_select_tag(options = {})
-        date_or_time_select options.merge(:discard_hour => true)
+        date_or_time_select(options.merge(:discard_hour => true))
       end
 
       def to_time_select_tag(options = {})
@@ -381,8 +387,15 @@ module ActionView
           discard[:minute] = true if options[:discard_minute] or discard[:hour]
           discard[:second] = true unless options[:include_seconds] && !discard[:minute]
 
+          # If the day is hidden and the month is visible, the day should be set to the 1st so all month choices are valid
+          # (otherwise it could be 31 and february wouldn't be a valid date)
+          if discard[:day] && !discard[:month]
+            datetime = datetime.change(:day => 1)
+          end
+
           # Maintain valid dates by including hidden fields for discarded elements
           [:day, :month, :year].each { |o| order.unshift(o) unless order.include?(o) }
+
           # Ensure proper ordering of :hour, :minute and :second
           [:hour, :minute, :second].each { |o| order.delete(o); order.push(o) }
 
diff --git a/actionpack/test/template/date_helper_test.rb b/actionpack/test/template/date_helper_test.rb
index f78819cfce..8f92840c78 100755
--- a/actionpack/test/template/date_helper_test.rb
+++ b/actionpack/test/template/date_helper_test.rb
@@ -784,6 +784,23 @@ class DateHelperTest < Test::Unit::TestCase
     assert_equal expected, date_select("post", "written_on")
   end
 
+  def test_date_select_without_day
+    @post = Post.new
+    @post.written_on = Date.new(2004, 6, 15)
+
+    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n"
+
+    expected <<  %{<select id="post_written_on_2i" name="post[written_on(2i)]">\n}
+    expected << %{<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6" selected="selected">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n}
+    expected << "</select>\n"
+
+    expected << %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
+    expected << "</select>\n"
+
+    assert_equal expected, date_select("post", "written_on", :order => [ :month, :year ])
+  end
+
   def test_date_select_within_fields_for
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)