For applications relying on the transfer of multimedia, and in particular continuous media, it is essential that quality of service (QoS) is guaranteed system-wide, including end-systems, communications systems and networks. Although researchers have addressed many isolated areas of QoS provision, little attention has so far been paid to the definition of an integrated and coherent framework that incorporates QoS interfaces, management and mechanisms across all architectural layers. To address this deficiency, we are developing a Quality of Service Architecture (QoS-A) which offers a framework to specify and implement the required performance properties of multimedia applications over integrated service networks. This paper provides an overview of the QoS-A, which incorporates the notions of flow, service contract and flow management. We then focus on the role of a multimedia enhanced transport service (METS) and show how QoS levels contracted by the transport service user can be assured in the context of our experimental local ATM environment.