The purpose of this Funding Opportunity Announcement (FOA) is to support a coordinating center (CC), which will coordinate research efforts across the NIDA funded longitudinal cohorts that address emerging and high priority research on HIV/AIDS in the context of substance use and substance use disorders (SUD). The CC will serve as 1) a national data and specimen resource that harmonizes and collects data and biological samples from the NIDA cohorts and affiliated studies, and enables additional research efforts through virtual repositories; 2) a facilitator of current and future research at the intersection of HIV and substance use and SUD; and 3) the central hub for organizing and enabling communication within and outside the NIDA cohort studies program, including annual meetings, advisory and scientific oversight committees.