In the early twentieth century, Leon Petrażycki founded the psychological school of legal philosophy at the St. Petersburg Imperial University. This school can be considered as an independent, local version of legal realism (its adherents include, inter alia, G. Guins, G. Ivanov, A. Kruglevsky, M. Laserson, P. Mikhailov, G. Gurvitch, N. Timasheff, P. Sorokin, S. Hessen, M. Reisner). The emergence of this school diversified the landscape of legal doctrine in Russia. The article describes and analyses the key ideas of the St. Petersburg school of legal philosophy led by L. Petrażycki and provides a brief overview of the main Russian conceptions of law which are closely aligned with legal realism. The author underlines the strengths and weaknesses of the psychological approach to the nature of law and offers his own version based on the communicative approach.