||This thesis examines the impact that colonial isolationist theory had upon childrearing techniques in treaty port China between 1881 and 1937. It works from the hypothesis that proper physical, moral, and identity development were all treated as components of good child health. It argues that obsessively isolationist practices resulted from the limited local hegemony held under extraterritoriality. Unable to institute farreaching hygienic regulations, the foreign community instead chose to insulate itself in foreign concessions and exclusive resort towns. The main goal of isolationist childrearing and education was to simulate an entirely Western environment and produce young adults who were virtually indistinguishable from their peers in the metropole. With the aim of investigating colonial isolationist theory and its workings, this thesis performs an indepth case study of Chefoo School, a highly regimented, theory-heavy boarding school in Yantai, China. In order to discuss ways in which isolationist theory evolved over the years, this study pays special attention to a major health crisis that occurred at Chefoo School in 1902. During the Chefoo School Calamity, 13 pupils died within three days of one another. The Calamity and resulting trial received much press and inspired the school to adopt a modern approach to hygiene. It also led to a form of institution-based isolationism that shored up physical boundaries against the outside world, emphasized strict routine, and relied on authoritarian surveillance of pupils and native servants.