Which Development Kit? Down this page, several and different versions of Development Kits (DevKit) are listed. Please download the right one for your version of Ruby: Ruby 1.8.6 to 1.9.3: tdm-32-4.5.2 Ruby 2.0.0: mingw64-32-4.7.2 Ruby 2.0.0 x64 (64bits): mingw64-64-4.7.2 Download Issues? Depending on your location, sometimes the downloads will not work.
Michael Hartl Contents Foreword