More than 20 percent of children in the United States experience a mental health condition. Yet 70 percent of those who need services are not able to access them. Most wait years before receiving intervention, inhibiting their progress in school and in life. As a place where we can reach most children, schools have the potential to help address this issue. In fact, the majority of students who do receive behavioral health services do so in schools. This report looks at how 70 schools in Boston are supporting students through an approach called the Comprehensive Behavioral Health Model (CBHM). The model, which is grounded in a belief that students who are mentally healthy will be able to access rigorous academic content, prioritizes social and emotional wellbeing with the same intentionality as reading and math. Through a partnership between Boston Public Schools, Boston Children’s Hospital, and UMass Boston, schools are implementing a Multi-Tiered System of Supports to reach every student. The report explores the launch, school-based implementation, and scaling of this model. In addition to providing a comprehensive profile of CBHM, it examines promising practices in other Massachusetts districts focusing on behavioral health.