application of concepts and methods from several subspecialties of the discipline (such as learning, motivation, and social psychology) to business (industry) and institutional settings.

The study of industrial-organizational (I-O) psychology originated in the United States in the early 1900s through the work of psychologists Hugo Münsterberg (Münsterberg, Hugo) and Walter Dill Scott (both of whom were trained by German physiologist and psychologist Wilhelm Wundt (Wundt, Wilhelm)), while its practical application developed largely through the work of American industrial engineer Frederick W. Taylor (Taylor, Frederick W.). I-O psychology grew rapidly after World War I and even more so after World War II.

Some I-O psychologists develop methods for personnel selection and training, while others analyze managers' styles and effectiveness or study ways to improve workplace morale, job satisfaction, and productivity. The field of I-O psychology contributed to the development of human factors engineering, or ergonomics, which involves designing equipment (e.g., displays for airplane cockpits and automobile dashboards, computer keyboards, or home appliances) that can be operated safely and efficiently. See also applied psychology.