It is possible. I currently have a jar deployed at a customer which contains both session and entity beans. All of them are in the same jar, and they share a single deployment descriptor (actually 2 descriptors, ejb-jar.xml and the server specific one). What I was saying is that I don't think you ever 'need' to set it up this way. It should always be ok to have 8 separate jars, 2 jars with 4 beans each, 4 jars with 2 beans, or just 1 jar with 8 beans. Any way you want to package it should work just fine. Personally I use the single jar because it's a lot more convenient for the client when it comes to deploying.