The Medicare outpatient prescription drug benefit (Part D), established as a voluntary program by the Medicare Modernization Act of 2003 with coverage starting in 2006, filled an important gap in the affordability of medical care for older Americans. All 49 million elderly and disabled Medicare beneficiaries have access to the drug benefit through private plans approved by the federal government. The standard benefit in 2013 has a $325 deductible and 25% coinsurance up to an initial coverage limit of $2970 in total drug costs. After this limit is reached, enrollees are responsible for a larger share of their drug costs until they reach out-of-pocket costs of $4750. Following this coverage gap, more generous benefits resume. Although the Patient Protection and Affordable Care Act of 2010 (ACA) made some important changes to Part D, in particular phasing out the coverage gap (or “doughnut hole”) by 2020, the cost of premiums, deductibles, and coinsurance still are a major obstacle to obtaining medications for many Medicare beneficiaries.