Within the research on immigrants’ health outcomes there is limited examination of how lack of citizenship adversely affects children’s Medicaid/CHIP coverage, access to care and health status in the United States. This dissertation pools data from the National Health Interview Survey from 2008 to 2015 on mixed-status families—families with at least one child that is a U.S. citizen and at least one child that is not a U.S. citizen—and employs family level fixed-effects to isolate the impact of noncitizenship (i.e. lack of U.S. citizenship) on children’s health, healthcare access and insurance coverage. After controlling for observable and unobservable characteristics shared across children living in the same family as well as age and gender, lack of U.S. citizenship lowered a child’s probability of being in excellent or very good health and of being covered by Medicaid/CHIP, and noncitizenship increased a child’s probability of experiencing delays in needed care due to cost. Although the author was unable to distinguish between children by their immigration status, results suggest that foreign-born children without U.S. citizenship do not exhibit health advantages relative to their native-born kin. At the same time, noncitizen children are disadvantaged in accessing needed healthcare services. The long-term public cost and public health implications resulting from these children’s experiences merit further examination.