The choice to include the human in the decision process affects four key areas of system design: problem representation, system analysis and design, solution technique selection, and interface requirements specification. I introduce a design methodology that captures the necessary choices associated with each of these areas. In particular I show how this methodology is applied to the design of an actual decision support system for satellite operations scheduling. Supporting the user's ability to monitor the actions of the system and to guide the decision process of the system are two key considerations in the successful design of a decision support system. Both of these points rely on the correct specification of human-computer interaction points. Traditional, computer-centered system design approaches do not do this well, if at all, and are insufficient for the design of decision support systems.