The article analyzes the formation, essence, and interrelation of the institution of citizenship within the system of international law. It examines the distinctions between the concepts of nationality and citizenship, as well as their role in international legal regulation. The legal consequences of multiple citizenship—particularly issues related to diplomatic protection, military service, and taxation—are also discussed. The policy of the Republic of Uzbekistan, based on the principle of single citizenship, is compared with international trends, and the national legal position is substantiated.