Southern Illinois University developed an instructional approach for supporting collaborative, problem-based learning (PBL) in medical education. A succession of software tools were developed and refined to implement this approach, and a technology-enriched facility, the "Collaborative Learning Lab" (CLL) was designed. The paper describes two types of software developed: software for the presentation and management of material for teaching cases, and data sharing groupware for use in PBL meetings. Detailed observational studies were undertaken of instructional meetings--conducted both with and without technology. These studies informed the design by making visible aspects of current practice that failed to serve the underlying theories of learning and instruction, thereby identifying opportunities for innovation. The studies supported assessment by revealing the effects of the innovation on the instructional process. (Contains 36 references.) (Author/SWC)