Here is what needed to get it working (I am using Rails 2.2 on Mac OS X)
1: Install the gem
Just get it from a default gem repository and make sure you use 'RedCloth' and not 'redcloth'.
$ sudo gem install RedCloth2: In your Rails app environment.rb file add two lines.
First specify this dependency with any others in the Rails::Initializer.run block. Don't worry about specifying a version.
config.gem "RedCloth"Second, add this require line at the end of the file:
require 'RedCloth'3: Get rid of any earlier versions of RedCloth.
You may not need this but I ran into issues with Rails picking up v4.0.1 even though the newer 4.2.2 was present.
$ sudo gem uninstall RedCloth --version <your older version>4: Restart your web server.
I run Apache2 and Passenger and simply doing 'touch tmp/restart.txt' did not solve my earlier version problem. Probably overkill but restart the server anyway.
5: That's it...