This book is a collection of materials from a special session of the VII World Sociological Congress in Varna, dedicated to the memory of V.I. Lenin and the study of his heritage. This collective work explores the essence of Leninism as a holistic socio-political theory. The book contains the largest part of the reports and messages made, revealing important issues of our time on relevant material. The authors consider the Leninist characterization of sociology and the identification of its place in the system of social sciences. In some articles, such fundamental socio-political problems as the leading role of the working class and its party in the revolution, the relationship of classes and social groups in socialist construction, the resolution of the national question, and the formation of communist labor were further developed.