BMP entity beans' persistence is all done by the bean developer. That means that you can use whatever method you want to load/store the bean's state -- even multiple tables, datasources, anything. However, note that where entity beans are persisted when using a database is a deployment/server issue. I'm sure some allow you to persist a CMP entity bean to multiple tables if necessary (subsets going to each, that is). In fact, I seem to recall JBoss giving this ability, although my memory sometimes plays cruel jokes on me. You'll have to investigate by looking at the jboss-cmp DTD. (This of course would alleviate you from having to deal with all the BMP issues -- a very good thing!) By the way, that was my Martha joke for the day. Exciting huh?