[Service system models for adolescent mental health in different institutional contexts and their implications for...

Based on health system and multi-level governance theories, this paper develops an analytical framework of "policy elements-implementation mechanisms-governance outcomes," covering seven dimensions: legal safeguards, financial commitment, service networks, human resources, digital/remote support, inter-sectoral collaboration, and early prevention and intervention. Structured coding was applied to Brazil, Australia, Germany, and the United States. The coding evidence is limited to laws, strategies, budgets, and project documents issued by governments or government-authorized agencies; materials from authoritative institutions such as the World Health Organization(WHO), the Organisation for Economic Co-operation and Development(OECD), the Australian Institute of Health and Welfare, and the U.S. National Center for Education Statistics; and peer-reviewed studies. The analysis reveals that Brazil, through its Unified Health System (SUS), the Psychosocial Care Network (RAPS), and the School Health Program (PSE), has developed a public health-oriented community integration pathway, although the distribution of dedicated child and adolescent mental health resources remains uneven. Australia has established relatively clear institutional linkages among its national strategy, public funding, the headspace youth service network, eheadspace digital support, and the Be You school mental health capacity-building initiative. Germany has formed a collaborative model combining social insurance and youth welfare, based on Social Code Book VIII (SGB VIII), statutory health insurance, and a common self-governance mechanism, yet it lacks a unified, nationally coordinated school-centered youth mental health service network. In the United States, schools have become a critical entry point for mental health services, with federal grants, Project AWARE, school-based mental health service subsidies, and the 988 crisis lifeline collectively driving service provision; however, insufficient funding and workforce shortages remain major constraints. Consequently, an effective adolescent mental health service system is not a replication of any single institutional model but rather the result of aligning policy elements, implementation mechanisms, and institutional contexts. For China, leveraging strong government coordination and an extensive education system, a hybrid service system should be constructed in which schools serve as key entry points, county-level and community services provide support, the medical system offers specialized backup, and digital tools play an auxiliary role. The continuity and equity of the system should be enhanced through mandated collaboration, sustainable financing, a tiered workforce, and outcome-oriented evaluation.