Ok, thanks for the clarification. So, as I understand it, managed transactions give me a transaction around the method, and managed PCs give me an injected EM - but this doesn't mean that the EM automatically joins the transaction? Searched the reference docs, but haven't found any mention on whether it works one way or the other... Still, the fact that it only breaks for transient entities and not for managed ones, is hard to explain (for me, anyway). Also, it only breaks when the @Out annotation is present, which makes it even more strange. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4034540#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...