So if you are in my situation, where you have a project using prototype and you want to use the jQuery date picker, you will notice that in certain situations, depending where your javascript is defined, you pickers won't work. The problem is the jQuery and Prototype $. You need to redefine the jQuery $ with anoter literal, like $j. So try this: <script type="text/javascript" charset="utf-8"> var $j = jQuery.noConflict(); $j(function() { $j('.date-pick') .datePicker({ createButton: false }) ......