Process models are a key artifact when designing and implementing modern enterprise applications. Process model change management is required to allow multiple users to work with models simultaneously. In this talk, we present the main concepts of our approach to process model change management which is based on compound operations and a process structure tree. We also report on our experiences concerning the technology transfer of a complex model transformation chain for process model change management. We conclude with a list of open research problems in the area of model-driven software engineering.