Substance use disorders remain among the leading causes of disability and premature death in the world, with rates remaining stubbornly high. Training with a rigorous methodological basis and a breadth of course work and research experiences is necessary to develop the next generation of scientists able to lead efforts to reduce the public health burden of substance use disorders. Accordingly, this renewal application seeks to extend the pre- and post-doctoral Drug Dependence Epidemiology Training Program, one of NIDA’s oldest continuously funded training grants now entering its 25th year in the Department of Mental Health at the Johns Hopkins Bloomberg School of Public Health. The goal of this training program is to produce the next generation of substance use epidemiologists who can address this need by: conducting research that will advance our understanding of the environmental and biological components of the etiology and natural history of substance use; developing, implementing, and evaluating interventions to prevent and control substance use; and critically examining substance abuse services, treatment and trends to improve substance abuse outcomes including HIV-related risk. We will train substance use epidemiologists who are able to tackle these challenges by emphasizing four focal areas in this iteration: (1) social and environmental factors; (2) genetic and biological factors; (3) treatment and services; (4) emerging trends. This training program will capitalize on the interdisciplinary resources at Johns Hopkins University to provide trainees with the skills and experiences needed to lead multi-disciplinary research that takes advantage of these emerging opportunities and promotes overall health and well being of communities. Trainees will achieve this through a rigorous program of coursework, research apprenticeships, and integrative activities that provide a solid foundation in the core proficiencies of substance use epidemiology. The program will include 7 predoctoral students and 7 postdoctoral fellows who are supported by an experienced group of 12 Core Faculty and 36 Affiliate Faculty. The trainees will be prepared to assume leadership positions in academia carrying out substance use epidemiology and HIV research typically as faculty in Schools of Public Health or Medicine, in government formulating research priorities and substance abuse policy at the local, state, national, and international levels, in private industry conducting applied research for pharmaceutical companies, and in non- profit agencies or non- governmental organizations advocating for those with substance use disorders.