In a component-based software system the different components communicate with each other through their interfaces, possibly using adapters. Whenever the requirements or the environment change, the component-based software system must be adapted accordingly.We present a method that supports a systematic evolution of component-based software at the architectural level. It is based on operators and modification schemata that help to identify different architectural alternatives to realize the evolution task. Furthermore, heuristics provide decision support to select among the determined alternatives.