Over the past 30 years, there have been major expansions in public health insurance for low-income children in the United States through Medicaid, the Children's Health Insurance Program (CHIP), and other state-based efforts. In addition, many low-income parents have gained Medicaid coverage since 2014 under the Affordable Care Act. Most of the research to date on health insurance coverage among low-income populations has focused on its effect on health care utilization and health outcomes, with much less attention to the financial protection it offers families. We review a growing body of evidence that public health insurance provides important financial benefits to low-income families. Expansions in public health insurance for low-income children and adults are associated with reduced out of pocket medical spending, increased financial stability, and improved material well-being for families. We also review the potential poverty-reducing effects of public health insurance coverage. When out of pocket medical expenses are taken into account in defining the poverty rate, Medicaid plays a significant role in decreasing poverty for many children and families. In addition, public health insurance programs connect families to other social supports such as food assistance programs that also help reduce poverty. We conclude by reviewing emerging evidence that access to public health insurance in childhood has long-term effects for health and economic outcomes in adulthood. Exposure to Medicaid and CHIP during childhood has been linked to decreased mortality and fewer chronic health conditions, better educational attainment, and less reliance on government support later in life. In sum, the nation's public health insurance programs have many important short- and long-term poverty-reducing benefits for low-income families with children.