Various events may be considered traumatic stressors, including combat experiences, sexual assault, accidents, natural disasters, and violent crime. Most individuals exposed to traumatic stressors do not develop posttraumatic stress disorder (PTSD); however, the high incidence of trauma exposure in the United States necessitates routinely assessing individuals for the presence of traumatic experiences and symptoms of PTSD . This course provides essential information regarding PTSD including diagnostic criteria, etiology, incidence, and effective therapeutic treatment methods. However, because not everyone exposed to an extremely stressful event develops PTSD, the course also describes resiliency and risk factors related to the development of PTSD.