Developing a large-scale institutional DSS designed to serve multiple managers in different business functions can be a more challenging task than that of developing the much more common one-user, one-function DSS that have evolved over the past few years. In this article we review some of the evidence suggesting that extra effort and rigor in the early planning and analysis stage of large-scale DSS development is worthwhile. We attempt to identify those characteristics of DSS that require different treatment than those available in traditional structured techniques. We then present, in the form of a case study, a hybrid technique which we refer to as DSA (Decision Support Analysis) which has been used effectively in developing large-scale institutional DSS. Finally, we discuss some of the positive and negative experiences that have emerged from using DSA.