Project Summary Despite recent emphasis on couples-based HIV prevention interventions, efficacious interventions for Latinx male couples have yet to be tested. The proposed study is a randomized controlled trial (RCT) of an HIV prevention couples-based intervention - Connecting Latinxs en Pareja (CLP). CLP is based on our team’s extensive formative work with couples, including remote delivery of study protocols and the use of biomarkers of adherence to HIV treatment and pre-exposure prophylaxis. CLP was specifically tailored to the needs of Latinx male couples. CLP, a four-session intervention grounded in social cognitive theory and a relationship- oriented ecological framework, has demonstrated high feasibility and acceptability in a recent pilot RCT and promising evidence of changes in key intervention mechanisms and outcomes. CLP is novel in that it (1) integrates both biomedical prevention techniques (i.e., pre-exposure prophylaxis [PrEP] and treatment as prevention [TasP]) and psycho-educational skill building; (2) offers culturally competent and linguistically appropriate information and education about options for PrEP and ART; (3) is driven by an HIV status-neutral prevention and treatment approach designed to address HIV prevention and care needs among seroconcordant (positive and negative) and serodiscordant couples; (4) employs an innovative algorithm for measuring HIV protection that goes beyond condom use as the sole indicator of HIV protection; and (5) is culturally tailored to Latinx couples to address social, environmental, and contextual factors that intensify HIV risk in this population including HIV-related stigma and discrimination. We will examine whether participants assigned to CLP report an increase in the proportion of HIV protected anal sex acts to those assigned to a Wellness Promotion (WP) time and attention matched control condition. The primary outcome, HIV protection, is operationalized with a validated composite algorithm as protected acts of anal intercourse (i.e., anal sex acts in which condoms, pre-exposure prophylaxis (PrEP), treatment as prevention (TasP), or a combination thereof, are used to reduce risk of HIV transmission) within the couple and with outside partners. We will recruit 150 Latinx male couples (N=300 individuals) from 50 Ending the HIV Epidemic (EHE) jurisdictions and an additional 17 jurisdictions with high HIV burden among Latinos. Follow-up will occur every 3 months over 9 months, and biological (self-testing for HIV and hair biomarkers for PrEP and ART adherence) and behavioral and psychosocial data will be collected. We will derive practical recommendations and considerations for key stakeholders to expand and improve implementation of CLP or other next steps as indicated by study results. To our knowledge, this study will be the first to examine the efficacy of a couple-based intervention to increase HIV protection for Latinx male couples capable of being scaled up to provide continuous s...