There has recently been considerable interest in quality of service management architectures for high speed networks. In contrast, however, there has been less research on appropriate architectures for mobile computing. This paper addresses the issue of quality of service in a mobile environment. In particular, we describe a distributed systems platform, Limbo, which is intended to support the development of demanding, mobile-aware distributed applications in a heterogeneous networking environment. This platform is based on the concept of tuple spaces and is extended with support for quality of service management. The emphasis of quality of service management is on monitoring and adaptation, although support is also provided for other functions such as admission control and resource reservation. The paper argues that there are significant benefits from using a tuple space paradigm in such an environment, particularly in terms of the ability to adapt to changes in network connectivity or the more general environment.