Population-based approaches to the primary prevention of posttraumatic stress disorder (PTSD) focus on the prevention of the stressor itself. Policy decisions also consider ways to allocate resources to best reduce potential damage from traumatic stressors and to ameliorate any resulting harm. A balance between broad risk prevention approaches and narrower treatment and recovery strategies can redistribute the risk of exposure and lead to fewer cases. Understanding that PTSD and its costs affect not only individuals who seek care, but also many others whose lives overlap with these individuals as well as society as a whole, further informs and shapes prevention decisions.