In this paper, we explore the unmet need for substance use disorder (SUD) treatment among youth, its consequences, and the opportunity to address this gap due to the expansion of behavioral health services to school-based settings under the Parity and Affordable Care Acts. We discuss the importance of using evidence-based approaches to assessment and treatment to ensure effectiveness and cost-effectiveness and show how the severity of SUD is related to a wide range of school, substance, mental, health, and health care utilization problems. Next, we introduce the other three articles in the special issue that further demonstrate the feasibility and impact of using these evidence-based practices in school-based settings, the challenges of identifying and interviewing with youth, and the need for a full continuum of interventions. In each of these areas we try to draw out the policy implication of these trends and papers.