An important element of most models, simulations, or games is the "scenario," which delineates the modeler's conception of whatever he is attempting to represent. This report focuses upon the designing of scenarios for the political/military free-form games, but the underlying assumptions regarding the function of scenarios will be shown to apply to a wide range of modeling exercises. This report considers such issues as the model's frame of reference, bounding the model, the role of theory, and data considerations. The credibility of the model and its "sensitivity testing" are also addressed. Although most of the examples are drawn from the author's experiences in writing scenarios for political/military free-form gaming, the report concludes by demonstrating how these issues are applicable to other forms of modeling such as John Crecine, [Governmental] [Problem-Solving] and Jay Forrester, [Urban Dynamics].