The MISSION (Multi-tier Integrated Supports for Suicide prevention Implementation and Outcomes in New York) Project proposes development of a Multi-Tiered System of Support (MTSS) for Staten Island adolescents and young adults ages 10-24 at risk for suicide. The project's catchment area is Staten Island, a diverse county with critical gaps in youth suicide prevention. We will focus on integrating prevention activities across the school district, two college campuses, and four major behavioral health organizations, including school-based, outpatient, inpatient, crisis services, emergency departments, and pediatric primary care. Our approach will offer Tier 1 prevention services to all students and strengthen Tier 2 behavioral health supports, including training adults to identify and refer at-risk youth to an integrated system for rapid closed-loop referrals and providing universal screening and evidence-based interventions in behavioral health settings. Lastly, we will develop a Tier 3 Suicide Prevention Specialty Partnership for crisis stabilization, suicide-specific interventions, and rapid response to divert from emergency services and address the specialized needs of youth with suicidal thoughts and behaviors. We will begin by building much-needed tier 3 provider competency/capacity and configuring bhworks, an innovative software solution for tier integration, before initiating broader early identification efforts aimed at connecting youth in need to services. The MISSION Project will leverage longstanding existing partnerships with the Staten Island Partnership for Community Wellness and build upon NYS’ prior downstream clinical Zero Suicide systems. We selected Staten Island for this implementation effort because it could have a large impact given the county’s high burden of youth suicide and overdose deaths, but also because Staten Island can serve as a good demonstration site for broader NYS dissemination: 1) its youth suicide rate is similar to NYS rates; 2) it is a relatively self-contained area where most residents receive education and healthcare locally; and 3) the borough reflects NYS’s rich racial, ethnic, linguistic, sexual orientation, gender identity, and socioeconomic diversity. The project will provide prevention activities to over 30,000 youth, tier 2 clinical services to 12,000 youth, and tier 3 crisis and specialty services to 2,500 youth over the 5-year period. While limited geographically to Staten Island, the MISSION Project will have broader implications for integrating youth mental health support across the other four boroughs of New York City as well as New York State more broadly.