The rise and demise of world communism was one of the great dramas of the 20th century. It was born in wars (World War I, World II), and offered an alternative vision of peace and modernity to that of the capitalist world. It was joined together for decades by a common commitment to “anti-imperialist struggle” under Moscow’s leadership. Ultimately, however, most of the sixteen states covered in this book succumbed to the pressures of the Cold War, capitalist globalization, the Sino-Soviet split, and popular disaffection. The result was either systemic collapse (the Soviet Union and Eastern Europe), fundamental economic reforms (China, Vietnam, Laos), or recalcitrant and brittle regimes (North Korea and Cuba). What lessons can be learned from the evolution and fates of communist regimes over the past century?The book traces communism’s arc: its origins in Marxism and Leninism; its victory in the Bolshevik Revolution of 1917; its construction of an international sub-system (the “world communist movement”); its spread throughout Europe and Asia (plus Cuba); and its ultimate demise, alteration, or stagnation. I focus on the sixteen states that were ruled by single-party, Leninist regimes that were initially committed to comprehensive social, economic, cultural, and political transformation of their societies.What, then, did communist revolutions and states have in common, in both their domestic and international orientations? How did they differ from each other? What were the appeals of communism that allowed them to come to power? Why did international communism fracture into competing models of domestic and foreign relations? Why did the Soviet Union and, with it, the world communist system ultimately collapse? Is there a future for new communist states?Informed by both a “comparative politics” and an “international relations” perspective, the book examines the relationships between regimes and their societies, the relationships among communist regimes, and the relations of these regimes with the United States and other capitalist powers. It is the interaction among these three sets of relations that is key to understanding one of the most tumultuous periods, and most powerful ideas, in modern history.One theme that runs throughout the book is the “drive to difference” among communist regimes after the death of Stalin. The Stalinist template for “building socialism” after the consolidation of power was either imposed or emulated—albeit to varying degrees—by all communist regimes. But after Stalin’s death in 1953, differentiation among communist regimes set in and intensified. These differences appeared in their internal policies, in their societies’ self-assertion, in their relations with each other, and in their relations with the capitalist world. The book categorizes these differing types of post-Stalinist and post-Maoist regimes, with special attention to the difference between “Bureaucratic Leninism” and “Market Leninism.”