Military personnel are at high risk for developing post-traumatic stress disorder (PTSD), historically 10 to 50% of all casualties. The best treatment is to provide an opportunity for rest and ventilation of feelings and then to return the person to duty and to his or her peer group. Preventing the cycle of PTSD from starting and thus decreasing psychiatric casualties is feasible. This can be done by promoting unit cohesion and morale, ensuring that individuals know their jobs, inducing stress during training so individuals will be better prepared to cope, providing realistic information about what to expect in combat, and holding group debriefings immediately after any traumatic event. This paper discusses various models for preventing PTSD and examines future directions for the prevention of PTSD.