The analysts and design of systems for decision support typically has taken a single methodology approach, ignoring the fact that DSSs vary in their scope, complexity and purpose. This paper examines three primary approaches to DSS analysis and design in order to begin formalizing a consistent framework for the selection of a DSS development methodology. The contingency framework emphasizes the conditions under which the various methodologies are appropriate and likely to be effective, and provides guidelines for matching decision situations with development approaches.