PROJECT SUMMARY / ABSTRACT HIV infection rates in the U.S. military have doubled since 2003, yet no interventions targeting HIV transmission in this population have been tested in over 15 years. Eighty percent of new infections occur among active-duty men who have sex with men (AD-MSM) – a population that is critically understudied due to a long history of policies that prevented researchers from asking service members about sexual identity or same-sex behavior. Permitted since 2012, research on behavioral health among AD-MSM remains scarce. Initial evidence suggests that HIV prevention for AD-MSM should target alcohol-related sexual risk behavior (AR-SRB). The causal link between alcohol use and risky sex is well established. Heavy drinking is prevalent among service members, highest among AD-MSM, and driven by highly pro-drinking military social norms. Alcohol misuse and risky sex are also both link to traumatic stress, particularly sexual assault, and AD-MSM have over 5 times greater odds of military sexual trauma (MST) relative to their straight male peers. Pre- exposure prophylaxis (PrEP), a common target of current civilian HIV prevention efforts, is less viable for AD- MSM due to significant social and structural barriers unique to the military – persistent stigma, absence of medical confidentiality, unavailability of PrEP at many installations, and prohibitions against its use by service members on deployment, shipboard, or in certain occupational specialties. Internet-based personalized feedback interventions (iPFI) are an ideal modality to address AR-SRB among AD-MSM. Delivered privately, iPFI has shown efficacy for reducing heavy drinking and related problems. The present 2-phase study seeks to develop a trauma-informed iPFI targeting both heavy drinking and sexual risk behavior among AD-MSM. Phase 1a: A survey of 160 AD-MSM will establish behavioral norms and provide data to test a novel behavioral framework describing traumatic stress and military culture as pathways to AR-SRB. Phase 1b: Qualitative interviews of 15 AD-MSM will contextualize AR-SRB and gather feedback on draft iPFI components. Phase 1c: We will finalize a novel iPFI based on findings and extant iPFI models. Phase 2: A randomized controlled trial (N=50) will provide data on intervention feasibility, acceptability, and preliminary efficacy. Pilot data will be used for an R01 application to NIAAA seeking to test the further-refined iPFI in a fully powered RCT. The training plan for this application will focus on growing expertise in intervention development, AR-SRB, behavioral responses to traumatic stress, AD-MSM health, and methodologies for research on stigmatized behaviors and hard-to-reach populations. A highly productive team of mentors is committed to Dr. Walton’s success and will each contribute unique expertise to his research and training plans. Support from this award is crucial to Dr. Walton’s development as an independent scientist, in the vanguard of schol...