Note that Sass is written in Ruby, so you’ll need Ruby installed as well. If you’re using OS X, it’s already there. Windows users can get it via the RubyInstaller for Windows. Linux users can install it with their package manager.

Standard Gem

Most people will just want the standard stable Sass gem. To install this:

gem install sass

Prerelease Gem

To get the latest and greatest Sass goodness, though, you’ll need something else. A prerelease gem is created automatically every time changes are made to the master branch. To install it:

gem install sass --pre

Installation from Git

Sass can also be installed directly from the Git repository:

git clone git://github.com/nex3/sass.git
cd sass
rake install

Downloadable Archives

Finally, archives of current and old releases are available on Rubyforge (even older releases are in the Haml project).