Abstract Background: Care coordination is essential to improve patients’ access to healthcare, clinical outcomes, enhancing patients experience, increasing provider satisfaction, and decreasing or maintaining costs, yet appears to be most successful for those with complex care needs. While the VA’s established primary care model, the Patient Aligned Care Team (PACT) has proven effective in increasing Veterans’ experience and trust while decreasing costs, many high need, high risk Veterans lack support for their complex clinical and psychosocial needs that impacts their health care use, outcomes and costs. Two major VA initiatives led by the Offices of Nursing Service (ONS) and Care Management and Social Work (SW), and the Office of Community Care (OCC) intend to address this gap with initiation of new care coordination needs assessment (CCNA) tools to match Veterans with the right level of care coordination and services in 2019. Yet, the CCNA tools and organizational processes have not been evaluated. Significance: Evaluation and implementation of effective care coordination practices are a high priority for the VA and is the focus of two major national initiatives to address MISSION Act access to care goals. Innovation/Impact: We will leverage ongoing initiatives, using routinely collected CCNA data, supplemented with health care use data, and Veteran and provider perspectives to systematically evaluate care coordination needs assessment tools, practices, and impacts on Veterans’ services received, outcomes and costs. Specific Aims: We will build evidence about the CCNA, processes, and outcomes for high need, high risk Veterans seeking VA covered healthcare at VA facilities and community sites. Our aims are to: 1. Characterize and compare the relationship between Veteran needs assessment, services received, health outcomes and costs for Veterans exposed to CCNA with a matched comparison group. 2. Survey and compare Veterans about their experience with care coordination services, integration with other healthcare services, and perceived health impacts. 3. Conduct formative evaluation to assess provider perceptions at early adoption VA sites about CCNA tools and processes related to determinants of innovation diffusion, care integration, and to inform and conduct a broader survey of providers. Methodology: We will use an organizational theoretical approach including care coordination and innovation diffusion frameworks to guide our research and employ an observational design using quantitative and qualitative methods. Veterans treated at early adopter sites beginning in 2019 and categorized as needing complex care based on the CCNA will be compared to matched Veterans using multiple data sources. Data sources will include Veteran CCNA from the CC/ICM and OCC sites; CDW, VA Community Care, Consult Toolbox, Medicare, vital status, and cost data. Survey data will be collected from Veterans and providers. Quantitative analyses will describe and compar...