Software process models must change continuously in order to remain consistent over time with the reality they represent, as well as relevant to the task they are intended for. Performing these changes in a sound and disci- plined fashion requires software process model evolution to be understood and controlled. The current situation can be characterized by a lack of understanding of software process model evolution and, in consequence, by a lack of systematic support for evolving software process models in organizations. This paper presents an analysis of the evolution of a large software process standard, namely, the process standard for the German Federal Government (V-Modell(R) XT). The analysis was performed with the Evolyzer tool suite, and is based on the complete history of over 600 versions that have been created during the development and maintenance of the standard. The analysis reveals similarities and differences between process evolution and empirical findings in the area of software system evolution. These findings provide hints on how to better manage process model evolution in the future.