Thanks for clearing this up. I removed the @DiscriminatorColumn annotation as suggested and now it does indeed work without the property set. I did some more googling and it seems JOINED inheritance is not well defined in JPA and varies based on vendor (http://en.wikibooks.org/wiki/Java_Persistence/Inheritance#Joined.2C_Multiple_Table_Inheritance). Some implementations require a discriminator column with JOINED inheritance.