Organized crime in Vietnam became big business and state authority in the decade following World War II. By the early-1950's, the most powerful group controlled large sectors of Sài Gòn's economy, the municipal police, the regional sûreté, and a private army of nearly three thousand. It would ultimately affect the unfolding of the Vietnam War. The group was called the Bình Xuyên, whose members were variously labeled as river pirates, bandits, and gangsters. My dissertation is a social history of the group and how its meteoric rise to power intertwined with broader processes of urbanization, decolonization, and state formation in 20th-century Vietnam. It asks: Under what conditions did this group form? How did it interface with state authorities and other claimants to political power? How did its turn from rural banditry to urban racketeering coincide with larger patterns of capitalist development and urbanization in southern Vietnam? Equally important, how did popular representations of the group reflect perceptions of political sovereignty, criminality, and governance in the context of decolonization? Analyzing archival materials and newspapers spanning the colonial-postcolonial transition and drawing on the scholarly literature on crime and outlawry from history, anthropology, sociology, and political science, my project will bring into focus the "criminal" as a constitutive part of modern Vietnamese history. As an empirical study of an extra-legal group thriving under conditions of state instability and war, my project also offers a valuable comparative case for understanding the political-criminal nexus.