The whole concept of modelling has caught on aided immeasurably by the considerable progress in computer technology. Mini-computers, timesharing systems, remote terminals, and graphical displays have placed computer power directly into the hands of the decision maker. This paper presents a corporate decision-aiding system, a family of timeshared models, developed for Xerox of Canada Limited (XCL) in an effort to link the functional areas for communication, planning, and control purposes. Using the approaches of statistical forecasting, heuristics, and simulation, the XCL Decision System assists and guides management all the way from deriving product demand forecasts to simulating the day-to-day operations of the firm to formulating divisional financial statements to preparing corporate operating and medium-range plans. Developed in a short time span and at low cost, the system is used extensively in Canada and has been adopted, in part, by U.S. corporate and regional offices.