Workflow systems are software systems that control the execution of long-term processes. Members of an organization are in charge of executing processes. A work assignment policy, i.e who should perform a certain piece of process, has to be modeled and implemented in workflow systems. Organizations may have a large variety of problems in work assignment, and it may not be feasible to devise a single model to cover all problems. In this paper, we introduce generality to work assignment design problems in workflow systems We provide a meta-model based approach which enables us to define arbitrary problem oriented work assignment policies.