Abstract: The subject of the study is dual nationality or bipatrism as a result of bilateral cooperation of states on issues of nationality. International legal cooperation of states on issues of nationality, in particular dual and multiple nationalities, is implemented through the conventional mechanism, that is, through the conclusion of bilateral and multilateral treaties. Treaty settlement of problems caused by the status of bi- and polypatrism is currently the most effective tool, because domestic norms, due to their unilateral action, are not able to fully respond to the newly emerging phenomena of interstate communication, among which the most urgent are the issues of nationality, in particular dual and multiple nationality. The author examines the differences between the terms "multiple nationality" and "dual nationality" on the basis of international agreements, in connection with which the conclusion is made about the lack of similarity in the content of these terms due to different legal regulation. The author analyzes the treaty practice on issues of dual nationality on the example of bilateral agreements. The author gives a modern classification of treaties on dual and multiple nationality, reflecting the current approaches of the states to these phenomena. The author concludes that despite the large number of bilateral agreements it is necessary to develop a new universal approach to the international legal regulation of multiple and dual nationality, which would reflect the current practice of legal regulation of bi- and polypatrism.