As far as I know JBoss 4.0.x does not yet support deploying a persistence archive with WEB-INF/lib . Its written in spec. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4015634#4015634 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4015634