Mental health issues among children and adolescents have increased, especially after the COVID-19 pandemic. Despite awareness, less than half get needed care, leading to long-term consequences. The World Health Organization calls for integrated, preventive community interventions. In this paper, we present The Mental Health Clinical Liaison Programme for Schools in the Community of Madrid, Spain, which features school-based activities delivered by multidisciplinary mental health teams, offering early detection, intervention, and prevention strategies for children and adolescents. We describe the activities implemented, present the evidence supporting them, provide preliminary data, and discuss the scope and challenges of the programme. In 2023–2024, the programme intervened in 53 primary and secondary schools, helping identify in 876 cases, evaluating 356, and referring 122 to other services. It supported interventions for 179 patients already in mental healthcare and 34 reintegrations after psychiatric hospitalization. Anti-stigma workshops have been conducted, involving approximately 1620 students. Ongoing research aims to evaluate the effectiveness and cost-effectiveness of these interventions to ensure continuous improvement in mental health services for young people.