Marxism-Leninism is the union of the most advanced revolutionary theory with the most advanced revolutionary practice. Lenin invariably emphasized the decisive importance of the experience of the revolutionary struggle and of socialist construction, of the experience of the masses, for a correct definition of the concrete paths of society's movement towards socialism and communism. The concrete paths and forms of communist construction may be disclosed and defined only by taking account of practical experience and by studying the tendencies of development in the socialist society. N. S. Khrushchev's report and the speeches of the delegates at the historic 21st Congress of the CPSU, as well as the resolutions of this Congress, contain a scientific substantiation and definition of the concrete paths, forms and methods of communist construction in the USSR.