Rapidly rising spending has prompted debate about increasing cost sharing in Medicaid and the Children's Health Insurance Program (CHIP). In this paper we assess the role of cost sharing in Medicaid and the CHIP and its potential financial burden on low-income families with children. We find that many families would face high health spending burdens even with minimal cost sharing for their publicly insured children. Adding even modest cost sharing for such children could greatly increase high financial burdens. Our results also suggest that implementing income-based caps on family spending can help address the burden of high spending for low-income families.