ABSTRACT Early HIV diagnosis is an essential component of the strategy to End the HIV Epidemic (EHE). Yet, half of the nearly 40,000 Americans who test positive for HIV every year have late (stage 3 AIDS) infection, which results in higher community transmission and poorer treatment outcomes. In the United States South, where HIV is disproportionately impacted, 50% of HIV infections are undiagnosed. Infrequent or delayed HIV testing is most often due to poor healthcare access and stigmatizing attitudes about HIV that inhibit prevention and treatment seeking. Thus, increased HIV testing access and uptake is urgently needed to normalize HIV testing and direct individuals to pre-exposure prophylaxis (PrEP) if they test HIV negative or HIV treatment if they test HIV positive. To increase HIV testing access and uptake, we propose integrating HIV prevention services within community pharmacies located in neighborhoods with high HIV prevalence. Despite promising evidence of feasibility of pharmacy-based HIV testing, it is not widely available. In fact, most local pharmacy boards lack policy guidance on HIV testing being within their scope of practice. Our work has shown that HIV testing uptake in community pharmacies can be increased if it is offered with less stigmatized non-HIV-related services (e.g., COVID19, blood pressure, glucose, and cholesterol screening). But many community pharmacy staff report inadequate training as barriers to integrating HIV testing into the pharmacy work system. Therefore, to evaluate the implementation and effectiveness of HIV testing and prevention services within community pharmacies we propose a hybrid type 1 study design that aims to 1) Examine the policy-, pharmacy staff- and client-level barriers and facilitators of adopting HIV prevention services (e.g., HIV testing, PrEP referral, HIV treatment referral) in community pharmacies, 2) Develop and implement pharmacy staff HIV prevention service (e.g., HIV testing and counseling, PrEP referral, HIV treatment referral) trainings, and 3) Test the effects of integrating HIV prevention services in community pharmacies with existing non-HIV-related screenings versus those without on effectiveness and implementation outcomes. Guided by the Exploration, Preparation, Implementation, Sustainment framework, this study will include an exploration phase that examines the barriers and facilitators to pharmacy-based HIV prevention service provision across the US South using online surveys of community pharmacy staff (n=300), and in-depth interviews of Board of pharmacy members (n=16) and pharmacy staff (n=40). In the preparation phase, a virtual community pharmacy HIV prevention training will be developed and offered to 150 community pharmacy staff. Finally, in the implementation and sustainment phase, we will evaluate the acceptability and sustainment of the HIV prevention service delivery over 12 months in 10 community pharmacies (5 pharmacies who offer primary prevention screenin...