This is the first report to examine the cost to the 50 states of public assistance programs for working families. We examine working families’ utilization of the health care programs Medicaid and Children’s Health Insurance Program (CHIP), as well as their enrollment in the basic household income assistance program Temporary Aid to Needy Families (TANF). Both of these programs operate with shared funding from the federal government and the states, and in this report we also examine the costs to the federal government of Medicaid/CHIP and TANF, as well as the Earned Income Tax Credit (EITC) and the food stamps program (Supplemental Nutrition Assistance Program, or SNAP). Our analysis includes only the cash assistance portion of TANF, and it does not include costs for state Earned Income Tax Credits, child care assistance, or other state-funded means-tested programs. Overall, we find that between 2009 and 2011 the federal government spent $127.8 billion per year on these four programs for working families and the states collectively spent $25 billion per year on Medicaid/CHIP and TANF for working families for a total of $152.8 billion per year. In all, more than half—56 percent—of combined state and federal spending on public assistance goes to working families.