This study will provide a certain type of exposure therapy, called prolonged exposure therapy (PE), to military Veterans with Post Traumatic Stress Disorder (PTSD). One hundred and seventy-five Veterans will participate in the study. The main study goal is to compare PE conducted in three different ways: (1) PE that is office-based (OB; Veterans come to a VA clinic and meet with a therapist via telehealth, using videoconferencing technology), (2) PE delivered via home-based telehealth (HBT; Veterans stay at home and meet with the therapist via telehealth, using videoconferencing technology), and (3) PE delivered in home, in person (IHIP; the therapist goes to the Veterans' homes to provide the psychotherapy). Symptoms of PTSD, depression, and anxiety will be examined at pre-treatment, post-treatment and at six-month follow up to determine if symptoms change over time. Study hypotheses state that the IHIP approach, compared to the other two approaches, will be more effective at reducing the PTSD symptoms experienced by these Veterans because it will help Veterans attend each session and complete the therapy "homework" assigned by the therapists (such as doing feared, but safe, activities around the house or the neighborhood). However, the delivery of IHIP may cost more than the delivery of PE via the other modalities.