Core M: Health Equity Sociobehavioral Science (HESS) Project Summary/Abstract The mission of the Health Equity Sociobehavioral Science (HESS) Core of the SD CFAR is to eliminate HIV disparities and achieve health equity through social and behavioral HIV research. In order to achieve HIV health equity, the HESS Core focuses on supporting HIV research with marginalized communities and stigmatized key populations, including racial and ethnic minorities, sexual and gender minorities, people who use drugs, and women in sex work. The specific aims of the Core are to: 1. Research Methods Unit: Promote excellence in social and behavioral HIV science by providing methodological expertise and services to our Center’s members. 2. Community Engagement Unit: Enhance the involvement of marginalized and underserved communities in HIV research by providing access to CABs and expertise in participant outreach and academic-community collaborations. 3. Mentoring Unit: Develop the next generation of health equity HIV investigators by providing mentorship and training in research methods and community engagement approaches specific to HIV disparities and equity research. The HESS Core is the only SD CFAR that provides expertise in sociobehavioral aspects of HIV. Innovations of the Core, its services, bidirectional community engagement activities, Community Advisory Boards (CABs), strategic collaborations that advance HIV policy research, and the inclusion of underrepresented minority Core faculty members who bring diverse cultural expertise enhance the breadth and depth of scientific expertise provided to SD CFAR members. Across the Core units – Research Methods, Community Engagement, and Mentoring Units – services include methodological advisement on sociobehavioral HIV research studies, identification of theory-informed, gender- affirming, and/or culturally-relevant survey measures and/or interview guides, feedback from the Health Equity CAB and/or Transgender/Nonbinary CAB, participant recruitment and retention strategies focused on underserved populations, and mentorship of underrepresented minority early stage investigators. Ultimately, the HESS Core services and tools can enhance and sustain impact on addressing health disparities among communities and populations that are marginalized and underserved, and who are in need of solutions to address social and structural barriers to engagement in HIV testing, treatment, and care.