The book considers theoretical psychology as the methodological basis of psychological science; a multi-level categorical system of psychology is shown, the historicism of methodological analysis is affirmed; explanatory principles of psychology (determinism, systemicity, development), its key problems (psychophysical, psychophysiological, psychognostic), the structure of psychological teachings and other methodological issues of psychological science are disclosed. The textbook is written in accordance with the requirements of the state educational standard and the program of the course "Methodological Foundations of Psychology," which is leading in the training of psychologists.