Cutting Out Stigma: A Barbershop-Based Cluster-Randomized Trial to Improve HIV Testing, PrEP Uptake, and Stigma Reduction - PROJECT SUMMARY/ABSTRACT Young Black men in the Southern United States experience a disproportionate burden of HIV and persistently low engagement in HIV and pre-exposure prophylaxis (PrEP) continua, driven in part by HIV-related community stigma and limited access to trusted, culturally responsive prevention resources. Although stigma reduction is widely recognized as essential to ending the HIV epidemic, most interventions target individual attitudes and behaviors, with less attention to the interpersonal, community, and health-system contexts in which stigma is produced and reinforced. To address this gap, our multidisciplinary community-academic partnership developed Cutting Out Stigma (COS), a theory-grounded, barbershop-based HIV prevention intervention that 1) trains Black barbers as Men’s Health Ambassadors, 2) deploys a culturally tailored multimedia campaign to reduce stigma and promote sexual health education, and 3) connects clients to HIV testing, and prevention services within or near these trusted community spaces. Barbershops serve as enduring social hubs for Black men and offer a unique platform to leverage peer influence, social learning, and direct connection to health services. Unlike traditional clinic-based HIV prevention strategies, COS leverages the unique social capital of Black barbers to extend the community health worker workforce to reach young Black men who may otherwise not receive HIV testing and PrEP services due multilevel barriers and builds on evidence-based multimedia strategies by activating barbers’ social media platforms to extend intervention reach beyond the barbershop. In a six-month pilot implementation trial across 26 Tennessee barbershops, COS demonstrated high feasibility and acceptability; reached over 25,000 individuals monthly through social media; facilitated more than 4,400 in-person health conversations; and was associated with significant improvements in HIV knowledge and reductions in community HIV stigma among barbers and their clients. Building on these findings, we propose a 1:1 parallel cluster-randomized hybrid effectiveness-implementation trial (involving 20 barbershops and 300 barbershop clients (Black men (ages 18–34) in 3 counties in Tennessee and Arkansas). Our central hypothesis is that COS will increase HIV testing and engagement in early PrEP continuum outcomes (HIV testing, PrEP awareness, referral completion) among young Black men, with reductions in HIV-related community stigma serving as a key mediating pathway. The study will assess intervention effectiveness, examine stigma as a mediator using mixed quantitative and qualitative methods, and evaluate implementation outcomes including reach, adoption, fidelity, cost, and sustainability using the RE-AIM and CFIR frameworks. Findings will generate rigorous evidence to inform scalable, community- centered HIV prevention strategies and advance NIMH priorities to address social and contextual determinants of HIV-related health disparities in high-burden Southern communities.