Thank you guys for your inputs. Jaikiran, the server.log is miles long, but I guess this could be a culprit. I think I am missing some jar somewhere... | ObjectName: jboss.j2ee:service=EJB3,module=MyEjb3.jar | State: FAILED | Reason: java.lang.NoClassDefFoundError: org/hibernate/util/DTDEntityResolver | Ruchi and Ferry: JBoss 4.0.5 with "JEMS install" supports EJB3, since, as mentioned earlier, EJB3Trail.ear is working fine on my server. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4050412#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...