Distributed teams can carry out critical tasks with appropriate decision support technologies. The architecture and detailed design of a Web-based GDSS, called TeamSpirit, are discussed to address the challenges of building a Web-based GDSS. A series of empirical studies are reported to assess the effectiveness of TeamSpirit in supporting distributed group problem solving when in-person facilitation is not possible. Results indicate that giving creative problem solving training to TeamSpirit participants had positive impacts on team performance. Users who received brief TeamSpirit training were able to design and facilitate virtual meetings by themselves and achieved better team performance than control groups. D 2005 Elsevier B.V. All rights reserved.