Despite its solid theoretical foundations, sophisticated conceptual models, and ability to generate findings generalizable to community populations, epidemiology’s potential for influencing advances in our understanding and treatment of substance use and other psychiatric disorders remains underused. Research on the etiology of psychiatric disorders tends to be guided by biologically based approaches, such as neuroimaging, animal models, and human organoids, rather than by population-based science; workforce distribution and availability of services seldom match estimates of need; preventive interventions are often based on theoretical models from prevention science, rather than from epidemiologic findings; and policy development rarely includes a process of systematic incorporation of epidemiologic evidence.