SWG TRSU: Project Summary/Abstract: The Translational Research on Substance Use (TRSU) Strategic Working Group (SWG) will connect expertise in community engagement with behavioral, basic and clinical scientists across the CFAR cores and broadly across the UCLA and CDU campuses. The TRSU will generate novel and high impact research at the intersection of HIV prevention, treatment and ART-free remission, and substance use/misuse (SU) by examining best practices from the perspective of participants in CFAR activities on how SU data is generated and used. The TRSU moves the field beyond existing approaches for measuring and intervening on substance use/misuse to examine acceptability and implementation challenges at the community level when studying rigorous characterization of SU exposure that can be used to examine impacts on the immune system, and the HIV reservoir. This TRSU will accelerate science in OAR priority areas by emphasizing that cultural relevance and community competency must be assessed for laboratory and behavioral assessments of drug products and SU exposure in individuals relevant to SU and misuse in the context of HIV infection. This will enable scientists working to understand the dynamics of the HIV reservoir in vivo to have better measures of SU, people working on improving rates of viral suppression will be able to obtain validated measures of SU exposure that are acceptable to the community, and those working on HIV prevention will be better able to identify those who can benefit from interventions to address SU disorders with identification of drug products in use. It also will examine how to feedback the findings on drug products and levels of use in local communities from laboratories and scientists in the CFAR to study participants and local care providers. These goals will be achieved by: identifying innovative methods for assessment of SU that can be used in studies of the HIV reservoir and immune reconstitution as well as in epidemiological, basic, and clinical science research to stop HIV. The TRSU will increase access to and stimulate support for multidisciplinary integrated assessments of SU and misuse such as hair sampling, drug product testing by strips/and or mass spectrometry in community settings, and ecological momentary assessments by bringing new investigators from outside HIV into this work. The TRSU will assess community acceptability of methods of assessment of SU most relevant to research on HIV prevention, treatment, and ART-free remission; and enhancing the dissemination of laboratory and clinical assessments of SU among research participants with the development of best practices for community engagement. The TRSU will enhance cultural relevance by engaging community participation in guiding development and use of research tools that can potentially advance intersectional studies of substance use/misuse and the three CFAR themes of HIV Prevention, Treatment and ART-Free Remission.