Classes call for cases—and vice versa OK, this is a very simplified class diagram. It is not exactly the way I would design it in real life (nor was it in a real project I was on), but the real-life design would tend to hide the truth behind the details. There is some amount of debate going on now about whether you should design the classes before, after, or concurrently with the use cases. I've done it all three ways, and tend to lean toward an iterative model, jumping back and forth between use cases and class design as a good solution. —LJJ