The problem I wanted to use some interface element in Rails that requires prototype.js so I had to have both librairies. The problem is that there's a conflict between them. Prototype.js doesn't seem to give a damn about it but jQuery is nicer with you. It offers a noConflict method. With Rails , prototype.js is the default librairie so to override this, you could do <%= javascript_include_tag "prototype", "jquery" %> <script>$j = jQuery.noConflict();</script> This way, you will have to use $j instead of $ to call jQuery. $ would still call prototype. Another thing you could do is to use jQuery on Rails and don't give a damn about scriptaculous. I personally prefer to use librairies that are fully tested instead of using a "by-pass" that could break my code. It's your choice… -- G SubbaRao ...