CoLab is a laboratory to experiment with new forms of computer-assisted collaboration. We argue that current tools for supporting meetings are antique. We propose experiments using modern computational and display technologies to build tools for better support of meetings and cooperative problem solving. Research objectives are outlined, specifically: the goals of the project and our approach to computer-based support for cooperative problem solving and the experimental basis for CoLab. We take a quick tour of the CoLab meeting lab being constructed. We outline an example tool and discuss some possible future tools. Previous software systems for supporting group work and some past efforts at structuring group problem solving are described. We present dimensions of tool design and some experiments under consideration. The basic architecture and the software primitives for group use of computers are presented. We discuss the current status of the CoLab project and our immediate plans. We plan to use CoLab to explore the use of computer software and advanced display devices to enhance and extend group problem solving activity. It will also be used as a laboratory to investigate appropriate structures for computer-based meetings.