Posttraumatic stress disorder (PTSD) can develop after exposure to a traumatic event and impacts roughly 5?8% of trauma-exposed individuals. Individuals with PTSD develop distressing intrusions, trauma-related avoidance, alterations in mood and cognition, and hyperarousal. There are both social and neurobiological factors that appear to confer risk for PTSD. There are high rates of psychiatric comorbidity, particularly with respect to mood disorders and substance use disorders. PTSD is associated with significant functional impairment and is likely to persist when untreated. Cognitive-behavioral psychotherapies, specifically prolonged exposure and cognitive processing therapy, have the most research supporting their use as frontline treatments for PTSD. Although effect sizes are not as robust as with psychotherapy, some of the selective serotonin reuptake inhibitors (SSRI) and serotonin-norepinephrine reuptake inhibitor (SNRI) medications are associated with benefits. Psychological debriefing methods are not recommended for the treatment of PTSD. With successful treatment, PTSD can remit, and individuals return to their premorbid level of functioning.