I have two classes - Admin and Viewer that are both subclasses of User. If I put: validates_uniqueness_of :login in the User class, then the behavior is not what I would expect. Login is validated only within the subclass, not the parent User class. I read about "scope" of this validation, but I don''t understand really what it is, and I can''t figure out a way to make the uniqueness validation work for all Users, no matter what subclass they belong to. Does anyone have any advice? Thanks Shelby