Medicaid enrollment trends for low-income children in both Illinois and the U.S. as a whole have been shaped by a series of major policy developments at the national level: federal mandates for gradual expansion of Medicaid coverage to all children in families below the federal poverty line, federal welfare reform legislation “delinking” Medicaid from family income assistance, and the State Children’s Health Insurance Program (SCHIP) giving states new options for extending health care coverage beyond federal mandates. By 2001, the convergence of these policy changes had resulted in a “quiet revolution” in health care coverage for children — a shift from welfare-based to income-based eligibility. Many more children are now eligible for either Medicaid or SCHIP, and the composition of medical assistance caseloads has changed dramatically. This report examines Medicaid enrollment for low-income children, the largest and most “visible” group eligible for Medicaid, in Illinois since 1991 and compares trends in Illinois with nation-wide trends and with those in other states. The comparative analysis, based on data from the federal Centers for Medicare and Medicaid Services, involves five other midwestern states and five states with the largest Medicaid programs. The report indicates that Illinois has not typically been at the forefront in moving beyond minimum federal mandates, but the state has made considerable progress in expanding eligibility for children in low-income families, especially in the past several years. The state also faces some ongoing policy challenges, which include reducing disparities in coverage of children and parents and closing the gap between eligibility and actual enrollment.