In 2009, the federal and state governments spent a total of more than $250 billion on health care benefits for the 9 million low-income elderly or disabled people who are jointly enrolled in Medicare and Medicaid. Medicare is a federal program that provides health insurance coverage to people who have disabilities, are diagnosed with certain medical conditions, or are age 65 or older (50 million people in 2009). Medicaid, which is funded jointly by the federal government and the states, provides health care coverage to low-income people who meet specific requirements for income and assets and other eligibility criteria (65 million in 2009). People who are eligible to receive benefits from both programs at the same time are known as "dual-eligible beneficiaries". All of those beneficiaries qualify for full Medicare benefits, but they differ in the amount of Medicaid benefits for which they are eligible. Seven million are "full duals", who qualify for full benefits from both programs. The other 2 million are "partial duals", who do not meet the eligibility requirements for full Medicaid benefits but qualify to have Medicaid pay some of the costs they incur under Medicare. This book examines the characteristics and costs of dual-eligible beneficiaries, focusing on 2009, the most recent year for which comprehensive data were available when the Congressional Budget Office (CBO) began this analysis. The book also examines the different payment systems that Medicare and Medicaid use to fund care for dual-eligible beneficiaries and recent efforts at the federal and state levels to integrate those payment systems and to co-ordinate the care that such beneficiaries receive from the two programs.