Hi. I have want to use the following arrangement: Model < CustomClass < ActiveRecord::Base My CustomClass has a bunch of code I want to be held in common to all my models. What happens however is that if I access a controller that uses Model, it works. Then on the second view (hitting reload) I always get: TypeError (superclass mismatch for class User): /app/models/account/user.rb:4 /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:207:in `load'' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:207:in `load'' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:39:in `require_or_load'' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:22:in `depend_on'' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:178:in `require_dependency'' /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/ active_support/dependencies.rb:178:in `require_dependency'' /usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/ action_controller/dependencies.rb:72:in `require_dependencies'' /usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/ action_controller/dependencies.rb:70:in `each'' /usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/ action_controller/dependencies.rb:70:in `require_dependencies'' /usr/lib/ruby/gems/1.8/gems/actionpack-1.11.2/lib/ action_controller/dependencies.rb:35:in `model'' .//app/controllers/account_controller.rb:4 I don''t understand why! Does AR modify the superclass in some way that makes extending model classes impossible? Thanks