The emergence and widespread adoption of the World Wide Web offers a great deal of potential in supporting cross-platform cooperative work within widely dispersed working groups. The Basic Support for Cooperative Work (BSCW) project at GMD is attempting to realize this potential through development of web-based tools which provide cross-platform collaboration services to groups using existing web technologies. This paper describes one of these tools, theBSCW Shared Workspace system—a centralized cooperative application integrated with an unmodified web server and accessible from standard web browsers. The BSCW system supports cooperation through “shared workspaces”; small repositories in which users can upload documents, hold threaded discussions and obtain information on the previous activities of other users to coordinate their own work. The current version of the system is described in detail, including design choices resulting from use of the web as a cooperation platform and feedback from users following the release of a previous version of BSCW to the public domain.