Companies today use business process management (BPM) to define, design, document and improve business processes. For the subtask of business process modeling, companies can choose from a large variety of existing modeling tools. The development of the tools challenges software vendors due to the growing number of requested features (resulting in so-called feature creep). Moreover, groups of heterogeneous clients are using the tools. Hence, participation of software users in the development process is necessary for designing 'usable' applications.