Current computer-based mechanisms for asynchronous communication include electronic mail and computer conferencing systems. Electronic mail supports one-to-many communication patterns and has serious drawbacks when used for group interaction. Computer conferencing systems are typically implemented to execute on a single processor and users at remote locations access the shared information by logging on from terminals connected by dial-up lines. This paper presents an architecture for a network-based system that models communication as group access to shared multimedia objects. It also describes the features of a computer conferencing system that was implemented for Bitnet, a network of academic computers, and Vnet, the IBM internal network.