Here's a summary of when to use inheritance and when to use containment: If multiple classes share common data but not behavior, create a common object that those classes can contain. If multiple classes share common behavior but not data, derive them from a common base class that defines the common routines. If multiple classes share common data and behavior, inherit from a common base class that defines the common data and routines. Inherit when you want the base class to control your interface; contain when you want to control your interface.