PROJECT SUMMARY. Persons with substantial functional disabilities--multiple limitations in activities of daily living (ADLs)--overwhelmingly prefer to remain at home. The VA faces a crisis in providing care for such Veter- ans, with increases in demand for long-term services and supports (LTSS) from 9.8 million older Veterans and one million younger injured post-9/11 Veterans. VA must by law provide nursing home care for Priority 1A and ≥70% service-connected Veterans, and also provide Home and Community-Based Services (HCBS) for all Vet- erans who qualify clinically. Although the law states LTSS must be provided in the least restrictive setting possi- ble, there is evidence that HCBS is underused/ VA still spends over two-thirds of its total LTSS budget on insti- tutional care, and GAO reports have identified persistent access barriers. Furthermore, our team found that only 50% of Veterans in Durham referred to HCBS used any services within a year. Underuse of HCBS poses a significant clinical care problem by failing to meet Veteran preferences and needs and may accelerate disabling events and costly institutionalization. And yet, we do not know the extent to which HCBS is underused, why it is underused, and the consequences of current use patterns. Shedding light on this question requires knowledge of the clinic, VAMC, and area-level factors that drive HCBS supply and demand. Evidence is thin because exist- ing studies were limited to identifying Veteran factors predicting HCBS use. To our knowledge, no studies have examined multi-level drivers of VA HCBS use among those referred, in particular, clinic-level drivers. Clinic struc- ture and processes will differ and while involvement of clinic social workers is expected to be vital given their role in making HCBS referrals, some clinics may have higher capacity for care coordination and routing of referrals. Additionally, VAMC and area factors may constrain HCBS use through LTSS funding choices, wait list rules, narrow networks, or workforce shortages. Homemaker home health aide (H/HHA) services will be our use case because H/HHA is the largest HCBS program (163,639 unique users in FY22) and, like most HCBS, is delivered through contracted providers. VA employees refer to H/HHA and care is provided by non-VA employees from community home health agencies. A rigorous mixed methods study is needed to illuminate multi-level drivers of H/HHA uptake and whether identified drivers reflect access supply barriers, Veteran preferences, or both. We also need to understand impact of H/HHA on Veteran-centered outcomes, using causal inference methods. We will address three inter-related aims: Aim 1. Identify multi-level drivers of any H/HHA uptake by 8 weeks (and 6 months) of referral compared to those with no H/HHA uptake by 8 weeks (and 6 months) among all newly referred Veterans nationally 2017-2020. H1. Veterans w/ pre-referral exposure to outpatient clinic social workers will be more likely to use H/HHA ...