Work ow systems hold the promise of facilitating the everyday operation of many enterprises and work environments. As a result, many commercial work ow management systems have been developed. These systems, although useful, do not scale well, have limited fault-tolerance, and are in exible in terms of interoperating with other work ow systems. In this paper, we discuss the limitations of contemporary work ow management systems, and then elaborate on various directions for research and potential future extensions to the design and modeling of work ow management systems.