PROJECT SUMMARY HIV, especially in the South, disproportionately affects young Black men who have sex with men (YBMSM). Development and implementation of effective interventions to scale up HIV pre-exposure prophylaxis (PrEP) are urgently needed in this population. Prior work has focused on individual-level approaches to increasing PrEP utilization, while social network-level approaches are comparatively underutilized. Individuals within social networks have access to social capital, which can yield emotional as well as instrumental resources that influence health behaviors. Black women represent a key source of social capital within YBMSM social networks, and this unique role has not been utilized in prior PrEP interventions. We propose to leverage YBMSM’s supportive connections with Black women to develop PrEP US NoW (PrEP Utilization through increasing Social Capital among YBMSM Networks with Women), a novel mobile health intervention that will engage Black women as facilitators in existing networks of YBMSM, as a way of enhancing social capital, decreasing intersectional stigma, and promoting PrEP uptake within the network. The proposal will pursue three specific aims: (1) Qualitatively evaluate core health-promoting elements of social capital bonds between YBMSM and Black women in extant social support networks; (2) Adapt an existing, evidence-based mHealth intervention to create PrEP US NoW; and (3) Evaluate feasibility and acceptability of PrEP US NoW, as well as preliminary efficacy to increase PrEP uptake among YBMSM, in a randomized-controlled pilot trial. For Aim 1, we will conduct qualitative interviews with n=20 YBMSM and n=20 Black women to gain insights into preferred attributes of Black woman facilitators, as well as feedback on intervention content and format. In Aim 2, we will develop the PrEP US NoW mobile app. The central feature of the PrEP US NoW intervention will be real-time, virtual discussions led by a trained Black woman facilitator, delivered to an existing network of YBMSM. Additional features and content will be refined based on our Aim 1 findings. We will conduct usability testing in an iterative process with both YBMSM and Black women. In Aim 3, we will randomize YBMSM networks (up to five members each), recruited using respondent driven sampling techniques, to the intervention (PrEP US NoW) or control study arm (mHealth app without social capital components). Participants (N=60) will complete validated surveys measuring social capital, internalized homonegativity, and PrEP uptake at baseline, 1-month, and at 3-months’ time. HIV testing will be done at baseline and at 3-months’ time. We will assess feasibility, acceptability, and preliminary efficacy. This study will be conducted in an epicenter of the Southern HIV epidemic: Alabama. Upon completion of our aims, we will have collected requisite preliminary data to inform a fully powered multi-site efficacy trial. The proposed research has strong potential to inform...