According to national indicators of adolescent health and well-being, the most significant health issues young people face are related to mental health. In San Mateo County, a recent report on adolescent health frames the prevalence of mental health needs among public school students as "staggering." Both locally and nationally, schools are grappling with the challenges of students' mental health needs, and the resulting demand it places on them not only to respond to students experiencing acute mental health distress, but to more effectively promote the mental health and well-being of all students. To address these challenges in Northern California's San Mateo County, San Mateo Union High School District, Peninsula Health Care District, and Stanford's Department of Psychiatry & Behavioral Sciences' Center for Youth Mental Health and Wellbeing have been collaborating to strengthen mental health supports for youth in both the high school district and its K-8 partner districts. To better understand which efforts have the greatest potential for impact, the authors joined their collaborative to conduct a mixed methods study to examine three questions: (1) How do students, parents, teachers, and providers perceive mental health needs and student supports throughout middle and high school?; (2) What predictive factors appear to be related to positive transitions, high school readiness, or risk indicators of later mental health challenges?; and (3) What are the opportunities for intervention and support to improve teen mental health? The research findings point toward four opportunities for schools and districts to transform their approach to supporting mental health and well-being: (1) Situate student mental health in the broader context of comprehensive development and well-being that is cultivated over the course of a lifetime; (2) Shift from an individual view of the problem and solution to a systems view; (3) Strengthen continuity of care across grades, schools, and districts; and (4) Expand data systems to include meaningful measures of well-being. [This report is a collaboration between the Gardner Center, the Stanford Center for Youth Mental Health & Wellbeing, and Peninsula Health Care District. For "San Mateo Area Teen Mental Health Study. Research Brief," see ED604088.]