This paper presents extensions to a well-known agent communication language for the expression of quality of service. It describes the semantics of the extensions, while allowing quality of service to be interpreted as broadly as possible. The paper then describes the specific extensions to KQML through added performative parameters. A prototype implementation of the extended language is also discussed. A version of this paper appears in the Proceedings of the 2001 International Conference on Artificial Intelligence, Las Vegas, Nevada, June 2001