This book presents the very first global treatment of eugenics. Eugenics emerged at the end of the nineteenth century as a global phenomenon that transcended religions, political orientations, and ideologies. It deeply influenced concepts of health care and state policies in many countries. Modern-day specialization and fragmentation of the historical profession have proven as ill-equipped to capture a global phenomenon such as eugenics and instead produced national or even regional studies of eugenics in which authors highlight the perceived national and regional specifics of eugenics in a particular setting. This book, by contrast, provides a history of eugenics that treats this global phenomenon in its complexity and its global span. It does not claim that eugenics in England, Germany, Canada, the United States, China and Japan was identical, but that developments in each country emerged from intensive contacts between eugenicists in these countries with each other. These eugenicists spoke the same language, followed similar trajectories, and shared a common vision.