In today's rapidly changing markets, organizations repeatedly change their structures. Existing workflow management systems reflect these structures in a separate organizational model and a process model (workflow model). However, these systems cannot cope with repetitive and frequent structural change of organizational and process structure and thus hamper continuous operation and quick reactions to turbulent markets. Change in the structure of the organizational model can cause orphaned references in the process model which leads to inconsistent workflow specifications. We describe the problem domain of structural change and classify it by eight categories. A powerful organizational meta model is introduced that allows to describe meta information about organizational structures. With this and with an underlying ontology, it enables workflow management systems to efficiently adapt to change. Finally, we show exemplarily how our approach is able to deal with the identified categories of structural change.