Workflow management systems (WFMS) are enjoying increasing popular ity due to their ability to coordinate and streamline complex organizational processes within organizations of all sizes. Organizational processes are de scriptions of an organization's activities engineered to fulfill its mission such as completing a business contract or satisfying a specific customer request. Gaining control of these processes allows an organization to reengineer and improve each process or adapt them to changing requirements. The goal of WFMSs is to manage these organizational processes and coordinate their execution. was demonstrated in the first half The high degree of interest in WFMSs of the 1990s by a significant increase in the number of commercial products (once estimated to about 250) and the estimated market size (in combined $2 billion in 1996. Ensuing maturity product sales and services) of about is demonstrated by consolidations during the last year. Ranging from mere e-mail based calendar tools and flow charting tools to very sophisticated inte grated development environments for distributed enterprise-wide applications and systems to support programming in the large, these products are finding an eager market and opening up important research and development op portunities. In spite of their early success in the market place, however, the current generation of systems can benefit from further research and develop ment, especially for increasingly complex and mission-critical applications.