The book by Professor E. P. Ilyin sets out in detail the theory and practice of differential psychology of professional activity. From it you will learn how individual personal and typical characteristics of a person influence the choice of type of activity and its effectiveness, how the specifics of activity influence the formation of personality traits and behavioral characteristics of a professional (professional deformation), and much more. The book is intended for psychologists and teachers and students of university faculties of psychological and pedagogical profiles.