HIV and Substance Use Cohort Coordinating Center for Emerging and High Impact Scientific Cross Cohort Studies: HIV SUCCESS - The purpose of the HIV and Substance Use Cohort Coordinating Center for Emerging and High Impact Scientific Cross Cohort Studies: HIV SUCCESS is to support National Institute on Drug Abuse funded cohorts as they implement research strategies to better understand and address substance use and its consequences among people with HIV (PWH). Substance use prevalence among PWH is high, and substance use patterns, including increasing concurrent methamphetamine/opioid use as part of the 4th wave of the opioid epidemic, continue to evolve. Substantial challenges remain to improve understanding and implementation of interventions to address substance use and its impacts among PWH. Addressing these challenges is the overarching purpose of the cohorts and requires a coordinating center (CC) experienced in data integration and harmonization, health informatics, multi-site coordination, clinical care and intervention experience, and HIV and substance use research to support the cohorts and comprehensively integrate cross-cohort data. The resulting resource of comprehensively integrated data will give researchers the potential to address important scientific and public health questions that would otherwise not be possible in individual cohorts. We will work with cohorts to allow complex, careful and complete analyses of outcomes and results across diverse populations using harmonized data. We will bring in data from other cohorts and studies as needed to ensure that adequate clinical, biomarker, and/or genetic data are available to address key questions. Careful data harmonization where appropriate will improve the statistical power to identify areas or sub-groups for research focus and to understand what interventions are proving successful in the broader context of the whole population of PWH (as opposed to the target population of a single cohort). This team brings vast experience with HIV cohort data; data linkage and harmonization; methods development; statistical support including causal inference from longitudinal observational data; health informatics platform and tool infrastructure and development including data repositories and tools for efficient and accurate electronically collected patient reported outcomes and outcomes adjudication; providing overall coordination for large collaborations of cohorts and studies; a strong background in clinical epidemiology of HIV and substance use; and expertise in applying this information to clinical care and interventions. We also have a comprehensive mentoring approach to develop a new generation of HIV and substance use researchers. We will support cohorts to enhance data collection where appropriate, merge and harmonize data when feasible, and work together to address key questions on HIV, substance use, and outcomes that cannot be addressed by individual cohorts. By providing project management, mentorship, and support, as well as developing a robust data repository, and accomplishing the integration and linkage of data, we will achieve a multi-disciplinary integrated network with multi-site data with sufficient sizes needed to address substance use and its impacts among PWH.