This second review of engineering psychology emphasizes the scientific and professional aspects within psychology of a broad interdisciplinary area of applied science variously called human engineering, human factors en gineering, biomechanics, biotechnology, ergonomics, or just human factors research and development. Obviously, there continues to be terminological confusion, if not anarchy, among those identified with the area.Following Fitts (53) , the emphasis of this review is placed on the identi fication of human performance functions which are relevant, not only to the initial design (or redesign) of equipment components of man-machine sys tems, but also to the determination of operational procedures and work environments for the human operator. Explicitly excluded are basic and applied studies relating to the selection and training of human operators.While this exclusion has certain practical merits, and is, in fact, reflective of a frequent neglect of individual differences and training variables in en gineering psychology research and applications, it should be recognized that the qualities of personnel and kinds of training determine human capabilities and limitations, and that they must be considered in the design of man machine systems, operating procedures, and work environments. As Melton (118) has pointed out, both engineering psychology applications and per sonnel and training research applications must draw upon scientific psy chology without arbitrary or bureaucratic restriction, if effective and effi cient man-machine systems are to be devised, even though the user of the engineering psychology recommendations is the systems engineer and the user of the personnel and training recommendations is the personnel system manager. Haire (72) has also made this point effectively in discussing en gineering psychology as a part of business and industrial psychology, while Christensen (39) makes the point in a paper on trends in human factors work.