diff -r 5c716437a83a Lib/argparse.py
--- a/Lib/argparse.py	Tue May 24 12:05:19 2011 +0200
+++ b/Lib/argparse.py	Thu May 26 19:42:26 2011 +0200
@@ -1969,17 +1969,12 @@
         # if we didn't consume all the argument strings, there were extras
         extras.extend(arg_strings[stop_index:])
 
-        # if we didn't use all the Positional objects, there were too few
-        # arg strings supplied.
-        if positionals:
-            self.error(_('too few arguments'))
-
         # make sure all required actions were present
-        for action in self._actions:
-            if action.required:
-                if action not in seen_actions:
-                    name = _get_action_name(action)
-                    self.error(_('argument %s is required') % name)
+        required_actions = [_get_action_name(action) for action in self._actions
+                            if action.required and action not in seen_actions]
+        if required_actions:
+            self.error(_('the following arguments are required: %s') %
+                       ', '.join(required_actions))
 
         # make sure all required groups had one option present
         for group in self._mutually_exclusive_groups:
diff -r 5c716437a83a Lib/test/test_argparse.py
--- a/Lib/test/test_argparse.py	Tue May 24 12:05:19 2011 +0200
+++ b/Lib/test/test_argparse.py	Thu May 26 19:42:26 2011 +0200
@@ -4480,6 +4480,40 @@
         else:
             self.fail()
 
+# ==========================
+# ArgumentContentError tests
+# ==========================
+
+class TestArgumentContentError(TestCase):
+
+    def test_argument_missing(self):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        parser.add_argument('x', type=str)
+        parser.add_argument('-y', type=int, required=True)
+        parser.add_argument('z', type=str, nargs='+')
+
+        with self.assertRaisesRegex(ArgumentParserError, 'x, -y, z'):
+            parser.parse_args([])
+        with self.assertRaisesRegex(ArgumentParserError, '-y, z'):
+            parser.parse_args(['myXargument'])
+        with self.assertRaisesRegex(ArgumentParserError, 'error:[\w ]+: z'):
+            parser.parse_args(['myXargument', '-y1'])
+
+    def test_optional_argument_missing(self):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        parser.add_argument('foo', type=str)
+        parser.add_argument('--spam', type=int, required=True)
+        parser.add_argument('--egg', type=bool, nargs='?', default=True)
+        parser.add_argument('--bar', type=int, nargs='?', default=1)
+
+        with self.assertRaisesRegex(ArgumentParserError, 'foo, --spam'):
+            parser.parse_args([])
+        with self.assertRaisesRegex(ArgumentParserError, '--spam'):
+            parser.parse_args(['first', '--egg false'])
+        with self.assertRaisesRegex(ArgumentParserError, 'foo'):
+            parser.parse_args(['--spam=1', '--egg', '--bar=22'])
+
+
 # ======================
 # parse_known_args tests
 # ======================