Although managed care seems to serve well the interests of non-elderly enrollees and their payers, elderly people face more risks. Chronic conditions, multiple problems, and more limited resources make them more vulnerable, whereas multiple payer sources make them more complicated to cover. This synthesis of managed care delivered in Medicare and Medicaid demonstration projects serving elderly beneficiaries shows that managed care plans either select or attract enrollees who suffer fewer frailties than those served in fee-for-service settings, exhibit reluctance to enter rural markets, provide a broad range of elderly-specific services, offer more comprehensive coverage and services, and result in greater perceived access problems, particularly for vulnerable subgroups. Plans operate more cheaply by using fewer resources, even after adjusting for case mix differences. Managed care enrollees tend to be more satisfied with financial and coverage aspects, whereas fee-for-service enrollees report higher satisfaction on other dimensions. In acute care settings, process of care findings were mixed, whereas clinical and self-reported outcome indicators were no better and in some instances worse in managed care. Long-term care enrollees, in the few studies reported, consistently faired worse in both the processes and outcomes of care. These findings suggest that further research on the effects of managed care in its rapidly changing incarnations is needed, particularly with respect to how to improve the quality of acute and long-term care delivered to elderly people and the proper role of government and other key actors in the health care system.