Using as Gem: gem 'gettext_i18n_rails' Using as plugin: gem 'fast_gettext', '>=0.4.8' Add "gettext" if you want to find translations or build .mo files Add "ruby_parser" if you want to find translations inside haml/slim files gem 'gettext', '>=3.0.2', :require => false, :group => :development gem 'ruby_parser', :require => false, :group => :development Rakes: rake gettext:add_language[XX] This will also create the locale directory (where the translations are being stored) where XX is the ISO 639-1 2-letter code for the language you