ON OCTOBER 26, 1977, the last case of naturally acquired smallpox occurred in the Merca District of Somalia. In May 1980, the World Health Assembly certified the world free of naturally occurring smallpox. The eradication of a disease was an unprecedented accomplishment. Eradication efforts for both paralytic poliomyelitis and dracunculiasis (i.e., guinea worm disease) are ongoing. Beyond the benefit to the world population's health and economy, smallpox eradication demonstrated the benefits of international commitment and cooperation toward a common cause in public health. Improvements made in international vaccination programs, global disease surveillance, and public health logistics systems that were results of the smallpox eradication program continue today.¹