Abstract: Although using the World-Wide Web as an information system has been practised for quite a while, there are only a few applications using the Web as a cooperation medium. The emergence and widespread adoption of the World-Wide Web offers a great potential in supporting cross-platform cooperative activities within widely dispersed working groups. The BSCW project (Basic Support for Cooperative Work) is attempting to realize this potential by development of Web-based tools providing cross-platform multimedia collaboration services to groups. In this paper we describe the BSCW system that we developed from 1994 on in order to support workgroup cooperation on the Web. The cooperation medium is based on the concept of a shared workspace where the communication between the workgroup members takes place. The paper gives an overview of the system architecture, studies the application field of multi-national project coordination and the development of the platform over the last six years and its adoption to the demand of more than 100,000 users from all over the world.