Project Summary Abstract Older adults with Alzheimer's disease and related dementias (ADRD) rely on a broad array of health and social services to address needs ranging from traditional medical care to supports for basic activities of daily living. A critical set of services is those that allow individuals with ADRD to remain at home as opposed to residing in an institutional setting. Referred to as home- and community-based services (HCBS), these services span from clinical services (e.g., skilled home health, in-home palliative care) to services that focus on custodial and social needs (e.g., home health aides, adult day, respite). Despite their widespread use, there is little data characterizing the organizations that deliver HCBS, or how well they coordinate with traditional institutional providers that also care for those with ADRD. Lack of accessible data precludes investigation into availability of HCBS across different geographies, scope of services offered, organizational relationships, quality, efficiency, and beyond. Addressing this gap is particularly essential for the ADRD population because they use HCBS at such high levels. Our proposal, submitted in response to NIA PAR-19-070, focuses on HCBS for those with dementia and offers a multi-method approach to capture systematic data on HCBS organizations and how well they engage in care coordination. Our approach leverages newly-available Medicaid claims/encounter data for HCBS to generate the first publicly-available, national-level datasets that list and characterize the organizations delivering HCBS to the ADRD population. Next, we will identify the organizational networks - including HCBS and institutional organizations – based on which organizations care for the same individuals. Prior work has defined networks of clinical providers that resulted in widely-used measures of healthcare markets (e.g., hospital referral regions). However, the definitions do not include HCBS. Defining networks that include