We recommend Ruby 2.1.0 for use with Rails. We stopped supporting Ruby 1.8.x after Rails 3.2. Ruby 1.9.2+ will be supported until Rails 5. Source: Compile it yourself Windows installer: Ruby, popular extensions, editor OS X 10.5+: Included with developer tools (then do gem update rails) We recommend managing your Ruby installation through rbenv. It’s an easy way to run multiple versions for diff