Welcome to IWQo S2001 in Karlsruhe! Quality of Service is a very active research field, especially in the networking community. Research in this area has been going on for some time, with results getting into development and finally reaching the stage of products. Trends in research as well as a reality check will be the purpose of this Ninth International W orkshopo n Quality of Service. IWQo S isa ver y successful seriesof workshops and has established itself as one of the premier forums for the presentation and discussion of new research and ideas on Qo S. The importance of this workshop series is also reflected in the large number of excellents ubmissions. Nearly 150 papers from all continents were submitted to the workshop, about a fifth of these being short papers. The program committee were very pleased witht he quality of the submissions andh ad the difficult task of selecting the relatively small number of papers which could be accepted for IWQo S2001. Due to the tough competition, many very good papers had to be rejected.