Abstract
The proportion of Medicaid beneficiaries enrolled in managed care plans has increased dramatically over the past decade. Whereas in 1991 only 9.5 percent of Medicaid beneficiaries were enrolled in some form of managed care, the proportion had grown to 55.6 percent by June 1999, at which point there were 17.8 million Medicaid managed care enrollees (1). Recent headlines announcing the withdrawal of major managed care plans from state Medicaid markets suggest the potential for significant disruptions to the care received by millions of Medicaid beneficiaries (2).