This paper discusses the lessons learned regarding system research through 20 years of building computer-aided systems to support group work activities and observing their use. These Group Work Support Systems (GWSS) have been defined as integrated computer-based systems which facilitate the solution of semi-structured or unstructured problems (DeSanctis and Gallupe, 1985). One focus of GWSS research has been on the nature of group communication processes in decision making meetings (hence the use of the term Group Decision Support Systems (GDSS) to describe these systems also) DeSanctis and Gallupe, 1987). However, computer-aided support for group work encompasses far more than just simple decision making activities. It includes planning, negotiation, consensus building, problem definition, expert system knowledge elicitation, system requirements specification, logical and physical system design, etc. In this paper we will focus on the use of GWSS in the system planning and development process.