Abstract: This pilot randomized clinical trial (RCT) sought to examine the preliminary efficacy of an internet-based version of written exposure therapy delivered to veterans through an online program supported by peer coaches. Veterans (N = 124) with clinically significant posttraumatic stress disorder (PTSD) symptoms were randomly assigned to imaginal exposure either via writing (written exposure) or verbal recounting (verbal exposure). The online treatment involved four to eight sessions of imaginal exposure preceded and followed by an online chat with a peer coach. Participants completed assessments at baseline, posttreatment, and 3-month follow-up. Half of the participants never started treatment; among those who started treatment, the mean number of sessions completed was 4.92. At posttreatment, participants in both conditions reported clinically meaningful improvements in PTSD symptoms, d = 1.35; depressive symptoms, d = 1.10; and functioning, d = 0.39. Although participants in both treatment conditions demonstrated significant improvements in PTSD symptom severity, equivalence results were inconclusive, as the 95% confidence interval of the change score difference exceeded the specified margin and overlapped with 0. Estimated mean change scores demonstrated that both conditions showed significant reductions at posttreatment and follow-up. Although engagement with the online program was a significant challenge, the findings suggest that written exposure therapy is effective for improving PTSD symptoms, depressive symptoms, and functioning when adapted for internet-based delivery and facilitated by peer coaches. Using technology to deliver exposure therapy and task-shifting the role of the therapist to peer coaches are promising strategies to increase access to effective PTSD care.