I'm not from JBoss/RedHad, but my guess is YES, you need the client jars from JBoss to access JBoss JNDI tree from a standalone Tomcat. The reason is, although the JNDI application programming interface is publicly defined by J2EE spec, the underlying communication protocol (between the JNDI server and client) is vendor specific, and if you need to connect to JBoss's JNDI sever, you need JNDI client classes which understand/talk the JBoss JNDI protocol. I believe the minimum set of jars you need to access JBoss JNDI is: jboss-common-client.jar jnp-client.jar But if you need to access other components like EJB, MQ, etc, you will also need other jars, and going with jbossall-client.jar would probably be the safest way to avoid ClassNotFoundException. Hope this helps. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4151639#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...