Book excerpt: This dissertation consists of three papers at the intersection of social policy and immigration. The first paper analyzes the impact of immigrant welfare exclusion on government social spending at both an aggregate and specific social program level, using cross-national social expenditure panel data from 21 Organization for Economic Co-operation and Development (OECD) countries between 1990 and 2015 and taking advantage of the significant variation in welfare exclusivity across OECD countries by year. The second paper utilizes the variation in states' response to the Affordable Care Act's Medicaid expansion to investigate its effects on low-income immigrants' inter-state mobility, specifically in-migration, and out-migration. Finally, the third paper utilizes data from the National Survey of Children's Health to examine the effect of the announcement of the Trump administration's revised Public Charge rule on insurance coverage and other health outcomes for children of immigrant parents.