This book constitutes the refereed proceedings of the Third International Workshop on Quality of Service in Multiservice IP Networks, Qo S-IP 2005, held in Catania, Italy in February 2005.The 50 revised full papers presented were carefully reviewed and selected from around 100 submissions. The papers are organized in topical sections on analytical models, traffic characterization, MPLS failure and restoration, network planning and dimensioning, Diff Serv and Inf Serv, routing, software routers, network architectures for Qo S provisioning, multiservice in wireless networks, TCP in special environments, and scheduling.