This article reviews studies that explore the relationship between access to medical care and children's health. The authors find that, on the whole, policies to improve access indeed improve children's health, with the caveat that context plays a big role. Focusing on studies that can plausibly show a causal effect between policies to increase access and better health for children, and starting from an economic framework, they consider both the demand for and supply of health care. On the demand side, they examine what happens when the government expands public insurance programs (such as Medicaid), or when parents are offered financial incentives to take their children to preventive appointments. On the supply side, they look at what happens when public insurance programs increase the payments they offer to health care providers, or when health care providers are placed directly in schools where children spend their days. They also examine how the Affordable Care Act is likely to affect children's access to medical care.