Computer aided systems theory is urgently needed for the design of software for CAD. New generation workstations together with the methods and tools of artificial intelligence allow the implementation of the powerful user-driven interactive systems required for CAST. Implementation of CAST software requires a sound meth- odology from systems theory, user functions tailored to specific applications, and a man-machine interface designed using latest results from cognition research and AI. Most of the papers in this volume are based on talks delivered at EUROCAST '89 held in the Canary Islands in February/March 1989.