Introduction: the article considers various approaches to the classification of private definitions, analyses the criteria for their division in the course of development of procedural legislation. This issue requires actualisation in procedural science in order to fully understand the essence and purpose of private definitions, as well as to improve their effectiveness. The aim of the article is to propose criteria for the division of private definitions that meet the current legislation and modern judicial practice. Methods: The author used the methods of comparative analysis, synthesis, generalisation of scientific materials and other general and special methods of scientific cognition. Results: based on the provisions of article 226 of the Code of Civil Procedure of the RF and article 188.1 of the APC of the RF, judicial practice and the results of scientific research, six criteria of classification of private determinations are proposed: by the subject who decides them; by the subject to whom the private determination is issued; by the plurality of subjects; by the initiating subject; by the grounds for issuing; by the nature of the committed offence. The expediency of expanding the subject composition of the institute of private rulings by including subjects of private law, such as individual entrepreneurs, legal entities and citizens is substantiated, which is conditioned by the development of judicial practice in this direction.