In the .NET world, ORMs are only just now beginning to see the light of day. Though nHibernate has been around for awhile, it has not seen much uptake from mainstream .NET devs. It may have to do with typical FUD stuff, like its roots in the Java world, its reliance on XML for the mappings, its learning curve, or the lack of books and beginner’s resources. I’m not judging - I’ve read this book and I think nHibernate’s offerings are the most mature and robust available for .