diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index ab49af55bf5c98aaa9c1a409122ef98ee64b0625..fb36262528c4e70f0de452a34da58a8ad24d516c 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -6,7 +6,6 @@
 require 'active_support/core_ext/string/access'
 require 'active_support/core_ext/string/xchar'
 require 'active_support/core_ext/string/behavior'
-require 'active_support/core_ext/string/interpolation'
 require 'active_support/core_ext/string/output_safety'
 require 'active_support/core_ext/string/exclude'
 require 'active_support/core_ext/string/strip'
diff --git a/activesupport/lib/active_support/core_ext/string/interpolation.rb b/activesupport/lib/active_support/core_ext/string/interpolation.rb
deleted file mode 100644
index 7f764e9de1dbd058a7aced054b705949dedf234f..0000000000000000000000000000000000000000
--- a/activesupport/lib/active_support/core_ext/string/interpolation.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require 'active_support/i18n'
-require 'i18n/core_ext/string/interpolate'
diff --git a/guides/source/active_support_core_extensions.textile b/guides/source/active_support_core_extensions.textile
index bf30ed64c85e5e40d723dbefc0d9d5fc369e670c..afd43ab317d14f3c9a8b9819a62534df88242b32 100644
--- a/guides/source/active_support_core_extensions.textile
+++ b/guides/source/active_support_core_extensions.textile
@@ -1277,20 +1277,6 @@ The <tt>inquiry</tt> method converts a string into a +StringInquirer+ object mak
 "active".inquiry.inactive?       # => false
 </ruby>
 
-h4. Key-based Interpolation
-
-In Ruby 1.9 the <tt>%</tt> string operator supports key-based interpolation, both formatted and unformatted:
-
-<ruby>
-"Total is %<total>.02f" % {:total => 43.1}  # => Total is 43.10
-"I say %{foo}" % {:foo => "wadus"}          # => "I say wadus"
-"I say %{woo}" % {:foo => "wadus"}          # => KeyError
-</ruby>
-
-Active Support adds that functionality to <tt>%</tt> in previous versions of Ruby.
-
-NOTE: Defined in +active_support/core_ext/string/interpolation.rb+.
-
 h4. +starts_with?+ and +ends_with?+
 
 Active Support defines 3rd person aliases of +String#start_with?+ and +String#end_with?+: