Mark active class
<html lang="en"> <head> <title></title> <link type="text/css" href="js/themes/base/ui.all.css" rel="stylesheet" /> <script type="text/javascript" src="js/jquery-1.3.2.js"></script> <script type="text/javascript" src="js/ui/ui.core.js"></script> <script type="text/javascript" src="js/ui/ui.draggable.js"></script> <script type="text/javascript" src="js/ui/ui.droppable.js"></script> <link type="text/css" href="js/demos.css" rel="stylesheet" /> <script type="text/javascript"> $(function() { $(".drag").draggable(); var dropOpts = { accept: "#drop1", activeClass: "activated" }; $("#target").droppable(dropOpts); }); </script> </head> <body> <div class="drag" id="drop1">drop1</div> <div class="drag" id="drop2">drop2</div> <div id="target">target</div> </body> </html>