Youth involved in the legal system (e.g., diversion settings, community supervision, confinement) experience a range of needs related to substance use risk and use behavior. Some youth might benefit from prevention programming to reduce the likelihood of initiating or escalating use of substances, whereas others need treatment for substance use disorders (SUD) or recovery services. However, few juvenile justice systems offer a full continuum of services to address these needs. We’d like to gain a better understanding of the resource and capacity limitations, gaps in intervention availability and implementation readiness, and other challenges that hinder systems’ ability to provide access to substance related services for this population. NIDA plans to convene an afternoon of roundtables to discuss the research gaps that, if filled, could improve access to a full spectrum of substance use services for youth in the legal system.