Prolonged exposure (PE) is an effective first-line treatment for posttraumatic stress disorder (PTSD), regardless of the type of trauma, for Veterans and military personnel. Extensive research and clinical practice guidelines from various organizations support this conclusion. PE is effective in reducing PTSD symptoms and has also demonstrated efficacy in reducing comorbid issues such as anger, guilt, negative health perceptions, and depression. PE has demonstrated efficacy in diagnostically complex populations and survivors of single- and multiple-incident traumas. The PE protocol includes four main therapeutic components (i.e., psychoeducation, in vivo exposure, imaginal exposure, and emotional processing). In light of PE's efficacy, the Veterans Health Administration designed and supported a PE training program for mental health professionals that has trained over 1,300 providers. Research examining the mechanisms involved in PE and working to improve its acceptability, efficacy, and efficiency is underway with promising results.