Two-thirds of children in the United States were income-eligible for Medicaid or the State Children's Health Insurance Program (SCHIP) at some point from 1996 to 2000. One in five children were income-eligible for both programs, and 73 percent of children ever eligible for SCHIP were eligible at other times for Medicaid. As SCHIP is reauthorized, Congress will need to give states the tools and financial commitment to assure that uninsured children are enrolled in and retain the coverage for which they are eligible.