In this paper we describe on-going work in protocol support for distributed multimedia applications. This work concerns the provision of suitable transport mechanisms to convey multimedia information (text, and digital voice and video) between multimedia workstations in a distributed system. There are two parts to the Lancaster multimedia work. First, we have developed an abstract model for multimedia communications based on the use of streams, and second, we have built an experimental system on which to test the implementation of protocols based on this model. This paper reports on both aspects of the Lancaster work, describing the results so far and identifying areas to be investigated further.