The diagnosis of post-traumatic stress disorder in veterans remains controversial, in part because little is known about combat PTSD. Most studies have been retrospective, so the question remains: What factors in a soldier who has not yet seen combat could predispose him or her to PTSD? Michael Telch and his colleagues are conducting what they say is the most comprehensive evaluation ever of potential risk factors. The project is unique in evaluating soldiers before they are sent to Iraq, assessing them throughout deployment using web-based stress logs, and reassessing them when they return. The study will provide information on possible genetic, brain, behavioral, social, and psychological factors that increase soldiers’ risk for PTSD and other combat-related stress disorders. That, in turn, could lead to more effective screening and prevention programs, reducing the incidence of these often debilitating disorders.