A detailed model for designing a Web-based Multi-Criteria Group Support System (MCGSS) is presented. The model is based on the Analytic Hierarchy Process (AHP) and uses the intensity of preferences of group members rather than simple voting procedures. This approach offers several advantages over simple voting mechanisms, including a much richer picture of both individual and group positions and more equitable decision-making. A prototype system, with a user-friendly graphical user interface (GUI), has been developed and used to analyze an experimental group decision process over the Internet. This permits a wider range of users, including those with limited typing skills, asynchronous communication across many time zones, and a larger number of participants than conventional systems. An agenda for further research is outlined.