In 1929, within five years of the death of Vladimir Lenin, Stalin was the ruler of the Soviet Union who flouted, abided, and applied the socialist principles of Lenin and Marx as political expediencies used to realise his plans for the USSR and for world socialism; most of which contradicted Lenin's plans for establishing socialism. Stalin justified his régime's deviations from Lenin's practices with the book Concerning Questions of Leninism (1926), in which Stalin represented Marxism–Leninism as a separate communist ideology, which featured an omniscient leader, hierarchies of one global communist party and communist vanguard parties in each country of the world. Stalin's interpretations of Lenin and Marx became Stalinism, the official state ideology of the Soviet Union.
As the Left Opposition to Stalin within the Communist Party and the Soviet government, Leon Trotsky and the Trotskyists argued that Stalin's Marxist–Leninist ideology contradicted Marxism and Leninism in theory and in practice, and thus was illegitimate socialist philosophy for the practical implementation of Socialism in Russia. Moreover, within the Party, the Trotskyists identified their communist ideology as Bolshevik–Leninism (Trotskyism), to politically differentiate their ideology from the ideology Stalin used to justify and implement his theory of Socialism in One Country (1924).
In Marxist political discourse the term Marxism–Leninism, denoting and connoting the theory and praxis of Stalinism, has two usages: (i) praise of Joseph Stalin, by Stalinists who believe Stalin successfully developed Lenin's legacy; and (ii) criticism of Stalin, by Stalinists who repudiate Stalin's political purges, social-class repressions, and bureaucratic terrorism.
Consequent to the Sino-Soviet split (1956–1966), in each socialist country, the Communist Party of China (CPC) and the Communist Party of the Soviet Union (CPSU) each claimed to be the sole heir-and-successor to Stalin, regarding the correct interpretation of Marxism–Leninism, and thus ideological leader of world communism. In that vein, the History of the People's Republic of China represents Maoism (urban Marxism–Leninism adapted to pre-industrial China) as Mao Zedong's fundamental up-dating and adaptation of Leninism to Chinese conditions, in which revolutionary praxis is primary and ideologic orthodoxy is secondary; and the Thought of Mao Zedong became the official state ideology of the PRC.
The Sino-Albanian split (1972–1978) was caused by Socialist Albania's rejection of the PRC's Realpolitik of Sino–American rapprochement, specifically the Mao–Nixon meeting (1972), which the anti-revisionist Albanian Labor Party perceived as an ideological betrayal of Mao's own Three Worlds Theory, which excluded such political relations of rapprochement. To the Albanians, the Chinese dealings with the U.S. were a lessening of Mao's ideologic and practical commitments to proletarian internationalism. Enver Hoxha, the head of the Albanian Labor Party, theorised an anti-revisionist Marxism–Leninism referred to as Hoxhaism, which attempted to retain an 'authentic' socialism in comparison to the post-Stalinist Soviet Union.
As revolutionary praxis, Maoism is the ideology of communist parties philosophically akin to the Communist Party of China. Since the death of Mao Zedong, in 1976, the Shining Path (Sendero Luminoso) Communist Party of Peru coined the term Marxism–Leninism–Maoism to identify the contemporary Marxism that is readily adaptable to local conditions in the countries of Third-world South America.