Project Summary Background. Miami is an HIV hotspot, driven by HIV disparities among Latino men who have sex with men (LMSM). Behavioral health problems (e.g., mental health, substance use) contribute to HIV acquisition, forming synergistic disparities. Yet, Latino MSM are underreached by proven HIV-prevention interventions (e.g., pre- exposure prophylaxis) and behavioral health treatments. The parent K23 is developing and pilot testing an implementation strategy (Dime Más) to increase the reach of PrEP, HIV testing, and behavioral health treatment to LMSM. Informed by the PI's preliminary data, the proposed supplement seeks to develop and pilot test another implementation strategy, which leverages LMSM peer influence, to enhance the reach of PrEP, HIV testing, and behavioral health treatment to LMSM. To advance health disparities science and achieve the Ending the HIV Epidemic goals, tailored implementation strategies are needed to ensure the equitable delivery of PrEP, HIV testing, and behavioral health services to LMSM. Research Strategy. Aim 1: Identify LMSM priorities for the content and design of the peer ambassador stories. From my preliminary data, I anticipate that the peer ambassador stories will be an app/website/forum that shows LMSM's personal stories of obtaining PrEP and behavioral health treatments. Users will interface by watching the peer stories and potentially chatting with peers within the platform. Results of two phases of formative research (interviews and theater tests with LMSM) will be used to refine the peer ambassador stories and develop the final module to be used in the pilot test. Aim 2: Pilot test the peer ambassador stories. Building on the parent K23, which is conducting a pilot test comparing Dime Más to standard outreach (control), I will utilize the proposed supplement to add a third arm to the pilot trial: the peer ambassador stories. LMSM will be randomized 1:1:1 to each condition (N=90, ~50% U.S. born). The supplement will evaluate the impact of the peer stories vs. control (and Dime Más vs. control) on health disparities by examining PrEP, HIV testing, and behavioral health uptake across groups and exploring mechanisms of effects. We will also examine implementation outcomes associated with the peer stories (e.g., appropriateness, acceptability, feasibility, cost) via exit interviews and surveys with participants and outreach workers. Outcomes. The proposed supplement will bolster the parent K23, which is developing and pilot testing Dime Más, an implementation strategy to enhance the reach of PrEP, HIV testing, and behavioral health services to LMSM, by adding a robust peer component. If the peer stories alone are acceptable and lead to increased uptake, the K23 will generate two strategies for increasing reach among LMSM, one which is intensive and one which is less intensive but potentially more scalable to lower resource settings. The findings will lay the foundation for a subsequent R01 effectiveness-implementation trial, further advancing scientific knowledge about these implementation strategies on LMSM disparities. This supplement will identify strategies for achieving HIV and behavioral health equity for LMSM, aligned with the EHE plan.