Puerto Rico faces persistent challenges in child and family mental health due to fragmented services, limited access to prevention programs, and structural poverty. Data from the ComPASS needs assessment across 21 municipalities revealed high rates of child maltreatment, elevated mental health service claims, and growing reliance on psychotropic medication among minors. These findings highlight the urgent need to move beyond individual-level interventions and toward multilevel, structural approaches that strengthen families, communities, and systems. This presentation describes the design and implementation of a structural intervention targeting midstream and systemic determinants of child and youth mental health. Guided by frameworks of social determinants of health and life-course development, the intervention was co-created through community consultations and collaboration with interdisciplinary experts from academic, clinical, and non-profit sectors. The intervention integrates three core components: (1) Workforce capacity building, equipping professionals with trauma-informed, data-driven practices; (2) Parental education and early prevention, strengthening parental competencies through home visiting and early childhood programs; and (3) Systems innovation, including the Mental Health Vulnerability Index for Minors, a decision-support tool that informs policy and resource allocation. Preliminary findings indicate that stakeholders view the multilevel approach as feasible and necessary, with particular emphasis on early prevention and cross-sector collaboration. Barriers identified include workforce shortages, fragmented data systems, and limited financial resources, while facilitators include strong community engagement and the integration of evidence-based frameworks. By addressing structural and midstream determinants, this intervention represents a critical shift in advancing equity and well-being for children and families in Puerto Rico. The lessons learned have implications for other contexts where systemic inequities undermine access to care and long-term developmental outcomes.