Medicare cost plans ¿ managed care plans paid based on the reasonable costs of delivering Medicare-covered services ¿ enroll a small number of beneficiaries compared to Medicare Advantage (MA), Medicare¿s managed care program in which the plans accept financial risk if their costs exceed fixed payments received for each enrolled beneficiary. This report: (1) determined the MA options available to beneficiaries in cost plans; (2) described key differences for beneficiaries between cost plans, MA plans, and Medicare Fee-For-Service; (3) determined the extent to which organizations offering cost plans also offer MA plans; and (4) described concerns cost plans have about converting to MA plans. Charts and tables.