Performanceevaluationhas beena discipline ofcomputersciencefor somethirty years. To us, it seemed to be time to take stock of what we - the performance evaluation community - were doing. Towards this end, we decided to organize a workshoponPerformanceEvaluationofComputer SystemsandCommunication Networks, which was held at the international conference and research center for computer science, Schlo Dagstuhl, Germany, September 15-19, 1997. The participantsdiscussed, amongotherthings, thefollowingfundamentalquestions: What are the scienti c contributions of performance evaluation? What is its...