From Java Persistence with Hibernate: "You probably won't need to use the theta-style joins often. Note that it's currently not possible in HQL or JPA QL to outer join two tables that don't have a mapped association -- theta-style joins are inner joins." When dealing with larger domain models (say, anything more than 100 entities) the number of permutations concerning how you could potentially want to correlate data in the system grows rapidly. However, the theta-style restriction makes providing a flexible mechanism for reporting difficult. I want to be judicious in my use of explicit relationship mappings, but this restriction seems to imply the exact opposite - that I'd have to use them freely in more places than I might have originally wanted to, and create an explicit mapping for everything that any reporting query might be correlated on. Would it be possible to relax this restriction, and allow the theta-style query to join on things that aren't explicitly mapped? -joe