Decision Support Systems (DSSs) have been defined in a number of ways by various researchers. The result is disagree ment and confusion. No one is quite sure of its exact definition. In this research, we have tned to redefine it by asking two basic questions: What things to support and how to support them? It is argued that critical activity analysis is a preferable starting point for a DSS design, and a DSS needs to support activities rather than decisions. A tool-kit framework for a DSS is presented for its design. Finally, a case study application is described where such a framework has been implemented in APL.