Publicly funded family planning clinics serve millions of low-income women each year, providing a range of critical preventive services and enabling women to avoid unintended pregnancies. It is important to quantify the impact and cost-effectiveness of such services, in addition to these health benefits. Using a methodology similar to prior cost-benefit analyses, we estimated the numbers of unintended pregnancies prevented by all U.S. publicly funded family planning clinics in 2004, nationally (1.4 million pregnancies) and for each state. We also compared the actual costs of providing these services ($1.4 billion) with the anticipated public-sector costs for maternity and infant care among the Medicaid-eligible women whose births were averted ($5.7 billion) to calculate net public-sector savings ($4.3 billion). Thus, public expenditures for family planning care not only help women to achieve their childbearing goals, but they also save public dollars: Our calculations indicate that for every $1 spent, $4.02 is saved.