JBoss classloading can be tricky. As a rough intro: Everything in an EAR sees everything else, with the exception of the WAR file. Nobody outside of the WAR sees what is inside the WAR. (there is a configuration option to change this) Classes are shared between EAR files, which can lead to some nasty problems if you aren't aware of what is happening. You can restrict the sharing of classes between EARs. It's fairly simple to do, and I personally recommend doing that for all your applications. It is almost always what you want to do. For more in depth info: http://wiki.jboss.org/wiki/Wiki.jsp?page=ClassLoadingConfiguration View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3989925#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...