When evaluating new vehicle designs, modeling and simulation offer techniques to predict parameters such as maximum speed, fuel efficiency, turning radius, and the like. However, the measure of greatest interest is the likelihood of mission success. One approach to assessing the likelihood of mission success in simulation is to build behavior models, operating at the human decision-making level, that can execute realistic missions in simulation. This approach makes it possible to not only measure changes in mission success rates, but also to analyze the causes of mission failures. Layering behavior modeling and simulation on underlying models of equipment and components enables measurement of more conventional parameters such as time, fuel efficiency under realistic conditions, distance traveled, equipment used, and survivability. We describe at overview and detailed levels the technical aspects of the tools and techniques we use to build these types of high fidelity human behavior models. We also discuss how these models can potentially be used to evaluate mission effectiveness of vehicle design. We close with brief descriptions of some of the deployed models we have built.