The EntLib 3.0 Hand-on labs haven't been updated for the april 2007 release. You may have to delete and add the references and update the App.config by replacing "2.0.0.0" with "3.0.0.0" and "PublicKeyToken=null" with "PublicKeyToken=b03f5f7f11d50a3a". Other than that, they're a handy intro. I finally have the chance to try these things out since the separate application block era.