Simulations are working representations of an event or incident. Case studies are indepth examinations of real or simulated situations to illustrate special and/or general characteristics. Exercises are tasks or problems designed to exert the mind or body toward the acquisition of knowledge. Simulation in initial police training often involves role play in which students enact scenarios to increase their problemsolving skills. Simulations, case studies, and exercises can be used to prepare for a known event, to examine a crisis that occurred in the past, to test new forms of police strategies or tactics, to evaluate equipment, to assess individuals' performance, and to provide opportunities for skill development. For simulations to be credible to participants, it is necessary that they equate with reality in content, process, and characteristics. Communication systems, interactive video, and computers are useful aids in simulation, and artificial intelligence and expert systems have created new possibilities for crisis simulation. Simulations provide a means for bridging the gap between theory and reality and for developing skills that are difficult to teach through traditional training methods. 30 notes and references.