This review of Medicaid and CHIP risk-based managed care over 2001-2010 shows that well-established programs exist in 19 of the 20 study states. While there is substantial variation across states, all the study states have developed ways to regularly select plans, define network requirements, and monitor access and quality. There is substantial stability in the number and types of plans. HEDIS and CAHPS data suggest that preventive care use has improved and that beneficiaries are generally satisfied with their health plans. Thus, the risk-based managed care programs provide a structure to absorb the newly covered adults under the Affordable Care Act, and provide a learning laboratory and important lessons for other states.