Here's a quick overview of Model View Controller architectures that was updated in April 2005. http://www.jdl.co.uk/briefings/MVC.pdf I haven't spent a lot of time thinking about this. 1) Modules represent the model. They are unaware of the view, theme. 2) View - To me there are three stock views, or outputs, in Drupal. The first is just themeless output. The second is the themed output. The third is as an XML-RPC request. 3) Controller-this is traditionally about controlling input. The controller knows about it's views. The question is, does Drupal have a controller, and if it does, is it the Forms API. This is a question that is consistently coming up in comparing Drupal to Ruby On Rails and I'd like to have a solid answer. Cheers, Kieran