But could someone confirm that EJB does support mapping a collection, and can load the items into the collection when the object is fetched? I see chapters on that in this book but I don't see any evidence that it is possible. I notice that when I persist my Customer object, the collection is never changed. Upon persistence, the collection should be converted into a proxy, but this obviously does not happen, leading me to wonder if EJB is even capable of doing that. If I were programming it, I would have the EntityManager.persist() method go through and call setters on all the objects it is persisting to replace their Collections with EJB proxies, but it ignores them. Either EJB doesn't support that use, or there is a bug in the EJB implementation. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3965901#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...