Abstract: We are investigating the use of computer technology to support collaboration among scientists and professionals. One component of this research is the construction of a distributed, real-time, digital video conferencing system on a network of high-performance workstations. This paper discusses the motivation for the construction of such a system and outlines the design of operating system and network support mechanisms for real-time communication of digital audio and video streams. We introduce a novel paradigm of inter-process communication called the real-time producer/consumer (RTP/C) paradigm. The RTP/C paradigm provides a framework both for expressing processor-time-dependent computations and for reasoning about the real-time behavior of programs.