The People's Republic of China, like the Chinese Communist Party that ruled it, was from its conception internationalist in premise and in promise. The PRC in its formative years would be Moscow's most faithful and self-sacrificing ally, a distinction earned in blood in Korea and by the fact that, unlike the East European “people's democracies,” the PRC's allegiance was not bought at gunpoint. This article researches one of the most ambitious international undertakings of that era: the effort to plan the development of half the world and to create a socialist world economy stretching from Berlin to Canton. What was China's role in this undertaking, and how did it shape the early PRC? How did this socialist world economy work (or not work)? How successfully internationalist was a project negotiated by sovereign (and Stalinist) states? Why did Mao Zedong ultimately destroy it, and with it, the dream of communist internationalism?