Beneficiaries with chronic diseases account for nearly two-thirds of all Medicare expenditures. The mandated Medicare Coordinated Care Demonstration tested specifically whether care coordination programs reduced hospitalizations and Medicare expenditures and improved quality of care for chronically ill Medicare beneficiaries in 15 demonstration sites. This third report to Congress synthesizes findings from more than four years of the demonstration programs’ operations, and provides the most comprehensive and rigorous estimates ever presented on the effectiveness of care coordination interventions in a Medicare fee-for-service setting. Only 2 of the 15 programs resulted in reduced hospital admissions, and none of the programs generated net savings. There were few effects on beneficiaries’ adherence to prescribed medication, diet, or exercise regimens. The report describes ways in which the more successful programs differed from the unsuccessful ones and concludes that programs with these features could generate savings for Medicare if implemented for a high risk target population.