This book provides a history of the origins of industrial-organizational (I-O) psychology, focusing on the late nineteenth century and early twentieth centuries. Taking an international perspective, The Early Years of Industrial-Organizational Psychology examines the context in which the field emerged, and its origins in the measurement of individual differences. Andrew J. Vinchur covers the initial applications of psychology in advertising, the study of fatigue, and especially employee selection, as well as the role industrial psychology played in World War I and the post-war expansion of the field. He also examines the education of industrial psychologists, their efforts to establish industrial psychology as a profession, and the beginnings of the organizational side of the field.