The textbook is written in simple and understandable language for all readers. The book will help the student to think systematically and understand the relationship between preventive, criminal, penitentiary psychology. The reader will also get acquainted with the work and principles of social and psychological expertise, learn about the activities of the state prosecutor in court, as well as with the lawyer in the trial.The textbook is prepared by Professor of the Department of Social Psychology, L. S. Vygotsky Institute of Psychology, Russian State University of Psychology, Doctor of Psychological Sciences, Professor Simonovich Nikolai Evgenyevich.