Architectural and hardware advances in computing design are occurring at an ever quickening rate, but it is the operating system that masters the complexity of these new computing devices to make them useful tools. Operating systems can make the difference between an interesting architecture and a useful computing environment. As more complex computational structures and more powerful communication technologies become available, we are faced with the need to develop new generations of operating systems to harness their power. This volume presents the proceedings of an international workshop intended to plot a course for design and development work on operating systems over the coming decade that was held in Dagstuhl Castle, Germany, in July 1991. Eight sessions covered: - Size, scalability and distribution in future operating systems, - The impact of future trends in hardware and communication technology, - Integrating heterogeneous operating systems, - Trends in real-time operating systems, - Fault tolerance support in futute operating systems, - Security and protection support in future operating systems, - The next generation of operating systems, - Supporting mulitmedia applications in distributed systems.