Upon his death, Lenin was succeeded as general secretary of the Communist Party by Josef Stalin. For thirty years (1924–1953) Stalin oversaw the evolution of MarxismLeninism into what is now known as Stalinism. Stalinism was responsible for the complete transformation of the Soviet Union's economy, politics, society, and culture, and for its development into one of the world's superpowers via a program of rapid industrialization. It was also responsible, however, for the deaths of millions of Soviet citizens who perished while Stalin's plans were being brought to fruition. As historian Stephen F. Cohen contends, "Stalinism was not simply nationalism, bureaucratization, absence of democracy, censorship, [and] police repression, . . . Stalinism was excess, extraordinary extremism, in each."

Prior to Stalin, socialist theory held that the fall of capitalism was imminent, and that the Soviet Union should serve as the vanguard for worldwide socialist revolution. Stalin rejected this notion in favor...