The objective of this article is to understand the political motivations underlying Medicaid managed care reforms by examining the determinants of enrollment of beneficiaries in managed care plans in the fifty states. To highlight the role of the model variables, including measures of the political environment, public interest, and special interests, a distinction is made between capitated and fee-for-service managed care enrollment. The results show that cost containment within the context of the Medicaid program is perceived as strongly favored by voters. Accordingly, the relative cost and tax price of providing Medicaid services are important factors in states' decision to enroll Medicaid beneficiaries in managed care plans, particularly capitated ones. The results also indicate a surprisingly significant influence by labor unions that generally oppose managed care enrollment for fears of lost jobs. The recipient population and provider groups also play an important role in shaping the Medicaid managed care landscape. The influence of variables measuring states' ability and willingness to pay and median voter preferences suggest that, within the context of Medicaid managed care enrollment, the public's interests are being served; however, the results also point toward inequities within the program and implications concerning financing arrangements between states and the federal government.