diff --git a/activesupport/lib/active_support/core_ext/string/inflections.rb b/activesupport/lib/active_support/core_ext/string/inflections.rb
index 15ad3d99cc..48e812aaf8 100644
--- a/activesupport/lib/active_support/core_ext/string/inflections.rb
+++ b/activesupport/lib/active_support/core_ext/string/inflections.rb
@@ -102,8 +102,8 @@ module ActiveSupport #:nodoc:
         # 
         #   <%= link_to(@person.name, person_path %>
         #   # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>
-        def parameterize
-          Inflector.parameterize(self)
+        def parameterize(sep = '-')
+          Inflector.parameterize(self, sep)
         end
 
         # Creates the name of a table like Rails does for models to table names. This method
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index e232bf8384..6c9b7e7236 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -77,6 +77,24 @@ class StringInflectionsTest < Test::Unit::TestCase
     end
   end
 
+  def test_string_parameterized_normal
+    StringToParameterized.each do |normal, slugged|
+      assert_equal(normal.parameterize, slugged)
+    end
+  end
+
+  def test_string_parameterized_no_separator
+    StringToParameterizeWithNoSeparator.each do |normal, slugged|
+      assert_equal(normal.parameterize(''), slugged)
+    end
+  end
+
+  def test_string_parameterized_underscore
+    StringToParameterizeWithUnderscore.each do |normal, slugged|
+      assert_equal(normal.parameterize('_'), slugged)
+    end
+  end
+
   def test_humanize
     UnderscoreToHuman.each do |underscore, human|
       assert_equal(human, underscore.humanize)
diff --git a/activesupport/test/inflector_test_cases.rb b/activesupport/test/inflector_test_cases.rb
index b7ac467c37..584cbff3e7 100644
--- a/activesupport/test/inflector_test_cases.rb
+++ b/activesupport/test/inflector_test_cases.rb
@@ -154,6 +154,22 @@ module InflectorTestCases
     "Squeeze   separators"                => "squeeze-separators"
   }
 
+  StringToParameterizeWithNoSeparator = {
+    "Donald E. Knuth"                     => "donaldeknuth",
+    "Random text with *(bad)* characters" => "randomtextwithbadcharacters",
+    "Trailing bad characters!@#"          => "trailingbadcharacters",
+    "!@#Leading bad characters"           => "leadingbadcharacters",
+    "Squeeze   separators"                => "squeezeseparators"
+  }
+
+  StringToParameterizeWithUnderscore = {
+    "Donald E. Knuth"                     => "donald_e_knuth",
+    "Random text with *(bad)* characters" => "random_text_with_bad_characters",
+    "Trailing bad characters!@#"          => "trailing_bad_characters",
+    "!@#Leading bad characters"           => "leading_bad_characters",
+    "Squeeze   separators"                => "squeeze_separators"
+  }
+
   # Ruby 1.9 doesn't do Unicode normalization yet.
   if RUBY_VERSION >= '1.9'
     StringToParameterizedAndNormalized = {