The Rockefeller Sanitation Commission’s hookworm eradication campaign in the American South during the 1910s led to an increase of 1 month in later-life longevity for those fully exposed in early life. Benefits were strongest among nonwhite individuals, children of illiterate mothers, and urban-born cohorts. Early exposure improved education, income, and cognitive ability, amplified by complementary policies like Rosenwald schools and child labor laws. The program generated an estimated $4.3 billion in longevity value, far outweighing its $27 million cost.