Long range planning is the process by which an organization assesses its h ture environment and develops specific plans of action to respond to, or change, that environment to achieve its goals. This report presents the results of a study of long range planning practices at one plant of a large US. computer firm, focusing on current and potential decision support systems (DDSs) for the quantitative aspects of the planning process. While it appears that the clerical tasks in the process can be computerized using current DSS technology, this technology does not help managers evaluate the credibility or quality of the plans made. An architecture is described for a system incorporating a much richer store of knowledge about planning variables which would allow the system itself to validate, explain, and justify its results. A concrete realization of such a system, called ROME, has becn designed and is currently under development. Design goals for ROME are presented and potential uses of the system are illustrated.