Global Population traces the idea of a world population problem as it evolved from the 1920s through the 1960s. The growth and distribution of the human population over the planet's surface came to deeply shape the characterization of "civilizations" with different standards of living. It forged the very ideas of development, three demographically defined worlds, and, for some, an aspirational "one world." Drawing on international conference transcripts and personal and organizational archives, Global Population shows how a geopolitical problem about sovereignty over land morphed into a biopolitical solution, entailing sovereignty over one's person.