Project Summary Children exposed to poverty experience poorer health compared to their peers; for children in foster care, these risks are compounded by maltreatment and out-of-home placement, resulting in even worse physical and behavioral health outcomes. Variation in healthcare use and health outcomes for foster youth is the result of the child welfare system, the caregiver, the individual child’s characteristics, and the healthcare system. Unfortunately, communication across healthcare and child welfare systems is disjointed, compounding health risk and increasing reactive and emergent healthcare use. The goals of this study are to evaluate the impact of healthcare delivery models on health outcomes for foster youth and understand factors associated with variation in healthcare use and health outcomes among children in foster care. To provide a holistic view of children’s functioning, this study leverages 12 years of linked child welfare and EHR data (N ~ 9,600 patients) in combination with Medicaid claims data and caregiver and self-reported health status for a subset of youth (N = 200) to accomplish three aims: 1) Evaluate models of healthcare delivery on healthcare use and health outcomes among foster youth as a result of: a) mandated visits alone; b) primary care, mandated visits, and specialty care delivered within the same healthcare system; and c) coordinated information sharing between healthcare and child welfare systems. 2) Identify causes of variation in healthcare use and health outcomes related to child welfare system (e.g., foster care status) and caregiver characteristics (e.g., perceptions of healthcare). 3) Understand how child characteristics (e.g., diagnoses, health risk behaviors, age, gender, race and ethnicity) contribute to variation in healthcare use and health outcomes over time. This is the most comprehensive examination of drivers of healthcare use and health outcomes among foster youth to date. Mechanisms identified through this grant that account for the most variation in health outcomes will be targeted in future studies evaluating how to modify healthcare delivery practices and collaboration across healthcare and child welfare systems to improve health outcomes for foster youth. By examining healthcare use and health outcomes, we will be better positioned to articulate where healthcare systems interventions parlay to better health outcomes.