Work presented in this paper focuses on the design of a computer-mediated system for supporting group planning on the World-Wide Web platform. It is shown that, by developing a set of appropriate intelligent tools and providing a public-domain application, any Web browser, such as Mosaic or Netscape, may be sufficient for an agent to take part in a planning procedure. The specific role of t he system is that of an assistant and advisor , recommending solutions and leaving the final decisions and actions to the agents. In other words, it emphasizes on a human-human coordination, communication and problem solving, rather than on a human-machine one. The proposed framework decomposes the problem of group planning into decision-making, uncertainty handling, constraint satisfaction and propagation, and integrates them appropriately.