The Province of All Mankind is the story of a powerful idea about the cosmos. Born in the science-fiction literature of the nineteenth century and maturing in the Age of Apollo, this idea held that outer space should be preserved as a "sanctuary" from human strife, free from weapons, warfare, and political rivalry. If humanity could somehow leave violence behind as it moved into space, perhaps peace would finally reign. Bucking a half-century of "space race" scholarship, Stephen Buono argues that despite waging a totalizing Cold War, the United States achieved stunning diplomatic successes that heralded the cosmos as a realm of peace and cooperation. The early story of space politics is not primarily one of militarization, but rather of political prescience and restraint. The Province of All Mankind demonstrates that space became a unique domain of American foreign relations and international law, and provides lessons for the Second Cold War unfolding over the horizon.