According to national indicators of adolescent health and well-being, mental health is one of the most significant health issues young people face. Since mental health is linked to other aspects of health and well-being, undiagnosed and untreated mental health conditions can negatively impact a young person's social-emotional health, academic outcomes, and overall quality of life. In San Mateo County, a recent report on adolescent health frames the prevalence of mental health needs among public school students as "staggering." Both nationally and locally, schools are grappling with the challenges of unaddressed mental health needs and the resulting demand it places on them to provide mental health services. To address these challenges, San Mateo Union High School District (SMUHSD), Peninsula Health Care District (PHCD), and Stanford's Department of Psychiatry & Behavioral Sciences' Center for Youth Mental Health and Wellbeing (Center for Youth), have been collaborating to strengthen mental health supports for youth in both the high school and K-8 districts. To better understand which efforts have the greatest potential for impact, they invited The John W. Gardner Center for Youth and Their Communities at Stanford University (Gardner Center) to conduct a study designed to answer 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? This research brief reports findings from that analysis and offers actionable opportunities for improving support for student mental health. [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. Executive Summary," see ED604087.]