The textbook contains materials for an experimental and theoretical study of the psychological aspects of the problem of human professional suitability. The essence of the concept and principles of creating a system for diagnosing and predicting professional suitability, as well as the history of the development of research in this area are outlined. Theoretical and methodological provisions on the main issues of the problem are substantiated. Methodological techniques for creating and implementing measures to determine professional suitability are analyzed. The results of experimental studies and the author's recommendations on some scientific and practical areas of formation and determination of professional suitability are considered. The book is intended for specialists in the field of psychology and labor physiology, engineering psychology, ergonomics, psychology students, as well as for teachers of psychology departments and students of non-psychological universities. 2nd edition.