The article considers the theoretical foundations of understanding the term "parliamentarism" based on the analysis of its nature and content and theoretical approaches to understanding the parliamentarism of such researchers as J. Habermas, P. Hellander, K. N. Sokolov, V. V. Maklakov, A. D. Kerimov, O. N. Bulakov, V. S. Zhuravsky, A. Z. Geogritsa, V. A. Smoliy, V. A. Zvirkovskaya and others. It is shown that the formation and development of Ukrainian statehood is inextricably linked with the idea and practice of parliamentarism. It is emphasized that the rule of law requires not only the rule of law and legal laws, but also proper legal organization of the system of state power, the establishment of various state bodies, a clear definition of their competence, place in the system, the nature of the relationship, methods of formation, forms activities, etc. Parliamentarism is analyzed as a multifaceted phenomenon with a complex internal structure consisting of interdependent elements. It is noted that parliamentarism characterizes the organization of public life, the achieved level of ensuring the rights, responsibilities and freedoms of citizens, ie the degree of democratization of society. It is stated that there is a wide range of opinions on the essence and principles of parliamentarism. It is concluded that only in the presence of organic unity of such characteristics and conditions as the presence of the institution of representative (legislative) power, formed on the basis of free elections with the participation of political parties and society; the constitutional principle of separation of powers; the rule of law; the presence of civil society, characterized by democracy and a high political and legal culture of citizens – we can talk about the presence of parliamentarism.