December 2, 2012, marks the 110th anniversary of the founding of what is today known as the Pan American Health Organization (PAHO). During its 110 years, PAHO and its member countries in the Americas have achieved such major health milestones as the eradication of smallpox and polio and the elimination of endemic transmission of measles and rubella. During the past century, life expectancy in the hemisphere has gained nearly three decades, infant and maternal mortality have declined significantly, water and sanitation services have expanded, and the gaps in health between rich and poor have narrowed. Pan American health cooperation has been an important contributor to this progress.