Introduces articles in the special issue of History of Psychology, Psychology and Psychiatry in the Global World Part I. The special issue seeks to consolidate and extend the historical analysis of psychology and psychiatry in the global world by bringing together seven articles detailing how theories, techniques, and practices have been translated, adapted, and appropriated in the colonial and postcolonial eras. The contributions demonstrate that it is fruitful to conduct research in the history of psychiatry and psychology together as broader ideational frameworks such as social Darwinism, eugenics, degeneration, and mental hygiene have inspired the development of psychological and psychiatric insights as well as the adoption of their intervention strategies worldwide. (PsycINFO Database Record (c) 2019 APA, all rights reserved).