The U.S. Army's concept-based requirements system stipulates that future materiel requirements should be based on a concept of warfighting that has undergone extensive analysis and refinement. This Note reports on the progress of an ongoing RAND effort to develop a method to help systematize and streamline the process of designing concepts. RAND's model will provide a first-order estimate of the forces and resources needed to meet specified theater success goals for alternative concept designs. The model is meant to be flexible and fast-running, in order to serve as a tool for the exploration of new concept ideas. Analysts using the model will be able to experiment with variations in operational policy, examine the payoffs of improved technical performance, and conduct sensitivity analysis to identify robust concepts.