PROJECT SUMMARY Sexual assault is highly prevalent among college students and is associated with high risk for alcohol misuse and co-occurring posttraumatic stress in survivors of all genders. These conditions are associated with significant strain on campus service systems and substantial short- and long-term consequences for students. Although effective preventative interventions (i.e., implemented within the months following trauma exposure) exist for these conditions, college student survivors often do not seek or successfully access in-person care, especially among men and racial/ethnic minorities. Mobile health (i.e., mHealth) interventions are a promising strategy to increase low-barrier access to preventative interventions among college students. We developed and pilot tested a multi-component mHealth preventative intervention prototype, THRIVE, to reduce posttraumatic stress and alcohol misuse in recent survivors of sexual assault. THRIVE was effective in reducing both posttraumatic stress and alcohol misuse, making it the first post-trauma mHealth intervention with evidence of efficacy in reducing alcohol misuse. In the current study, we propose to conduct an optimization trial to identify the most effective, efficient, and low-burden version of THRIVE for college students. Prior to conducting the trial, we will revise THRIVE using the real-time user feedback collected in the pilot trial (Aim 1). Revisions will maintain the core elements of THRIVE while increasing usability. Revisions will be selected by reviewing the app and pilot user feedback in partnership with user experience/interface designers, our advisory board of experts in cultural adaptations of interventions, and our advisory board of college student survivors. This will maximize usability with attention to the needs of diverse student survivors. Using the revised app, we will then conduct a 2x2x2 factorial randomized trial to test the unique effects of the 3 core THRIVE components (i.e., in-app activity scheduling, in-app cognitive restructuring, phone coaching) on alcohol misuse and posttraumatic stress (Aim 2), as well as the added benefit of coaching to activity scheduling and cognitive restructuring (Aim 3). N=464 college students with past-12-week sexual assault, elevated drinking, and PTSD will be enrolled. All participants will receive an onboarding call and non-core app elements (i.e., self-monitoring, encouraging statements banner, referrals), and will be randomized to additionally receive combinations of the 3 core elements. Participants will complete self-report assessments at baseline, daily during the intervention, post-intervention, and 3, 6, 9, and 12 months. Results will be used to select an optimized version of THRIVE. Our design will ensure that future testing and dissemination of THRIVE reflects maximally inclusive, efficient, and effective intervention elements. If effective, THRIVE would represent a highly-scalable strategy that could be directly imple...