Enacted in 1965, Medicare enrolled its first beneficiaries in 1966. Medicare has provided access to health care for tens of millions of Americans aged 65 and older, as well as to younger individuals with disabilities. To mark its 60th anniversary, it is fitting to review Medicare's many accomplishments, as well as its problems, and highlight reforms that can extend and build on its legacy. The problems mainly relate to the financing challenges the program poses, for beneficiaries, taxpayers, and the federal budget, and the approach that has led to significant overpayments to private Medicare Advantage plans that now enroll over 50% of beneficiaries. This article reviews historic trends in enrollment and spending in Medicare, payment innovations the program created, how traditional Medicare has outperformed commercial insurers in controlling health care spending, and sources of overpayments in Medicare Advantage. Finally, the article highlights potential ways to fix Medicare's problems and promote its sustainability for future generations.