Abstract: OBJECTIVE: Web-based prolonged exposure therapy (Web-PE) has potential to increase the reach of effective posttraumatic stress disorder (PTSD) treatment. While there is initial support for the efficacy of Web-PE, no studies have examined the perceptions and experiences of participants receiving PE in this novel, Web based format. METHOD: We used a mixed-methods convergent design to examine and integrate quantitative and qualitative data of participant perceptions and experiences of Web-PE. Treatment-seeking active duty military personnel or veterans (N = 29) who received Web-PE completed posttreatment surveys about perceptions of Web-PE and a brief qualitative interview. Thematic coding was used to identify qualitative themes, which were integrated with quantitative data in a joint display. RESULTS: Although many were initially skeptical of experiencing benefit, participants reported that Web-PE was helpful. They appreciated the flexibility of online therapy and reported that self-motivation was important for engagement. Web-PE therapists were well-regarded, although additional therapist support and technical improvements to the Web-PE program were suggested. Scores on the perceptions of Web-PE survey, PTSD survey, and other quantitative data corroborated the qualitative themes. CONCLUSION: Perceptions and experience of Web-PE are favorable and help to highlight the strengths (e.g., flexibility) and challenges (e.g., requiring self-motivation) associated with Web-treatment for PTSD. The results of this study may inform further development of Web-PE or other Web-based treatment programs.