ABSTRACT Work∞ow systems have long been of interest to computer sci- ence researchers due to their practical relevance. Support- ing delegation mechanisms,in work∞ow systems is receiving increasing research interest. In this paper, we conduct a comprehensive study of user delegation operations in com- puterized work∞ow systems. In a work∞ow system, the semantics of a delegation op- eration are largely based on three factors: the underlying work∞ow execution model, task type and delegation type. We describe three difierent work∞ow execution models and examine the efiect of various delegation operations in each work∞ow execution model. We then extend our work∞ow execution models to examine the efiect of various delegation operations in difierent role-based work∞ow execution mod- els. Categories and Subject Descriptors