Architectural and hardware advances in computing design areoccurring at an ever quickening rate, but it is theoperating system that masters the complexity of these newcomputing devices to make them useful tools. Operatingsystems can make the difference between an interestingarchitecture and a useful computing environment. As morecomplex computational structures and more powerfulcommunication technologies become available, we are facedwith the need to develop new generations of operatingsystems to harness their power.This volume presents the proceedings of an internationalworkshop intended to plot a course for design anddevelopment work on operating systems over the coming decadethat 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.