I don't want to pollute the ActiveRecord class by making the acts_as_chicken available to all of its classes. It must be made available only to the sub-classes of the ActiveRecord that has the acts_as_chicken declaration. On Mar 11, 9:33 pm, "eden li" <eden... / gmail.com> wrote: > It's still really unclear what you're asking (at least to me). Are > you saying you want acts_as_fox to work only if the object has fox == > true (and the same for chicken)? > > Or, are you talking about single table inheritance? If so, you can > just add acts_as_XXX to your sub-classes as appropriate... >