The development of a planning/budgeting model as an integral component of a decision support system is described. The case study approach is used to describe how Grambling State University (GSU) developed the model to improve its financial planning and budgeting processes. The model can be used for tactical and/or strategic planning. The model is discussed as an example of GSU's simulation/forecasting capability. The following four basic computerized data files are used to make extrapolations: credit hours, enrollment, personnel, and fee table. With the data files and output generated from other models, the model can be used to prepare simulations and forecasts about students, faculty, staff, state appropriations, other revenues, expenditures, surpluses, and deficits. An important feature of the planning/budgeting model is that the user can change the data elements. In addition the planning/budgeting model integrates data generated by other models, i.e., the salary planning, enrollment/recruitment, and institutional cost index models. Appendices provide detailed descriptions of the various data elements that are contained in the four basic files. Also included are a list of outputs generated by the planning/budgeting model, and examples of calculations that are performed by the model. (SW)