This dissertation explains when democracies will begin to develop legal institutions to combat organized crime as well as the extensiveness to which they will develop such institutions. I identify two types of institutions that are particularly important for countries looking to establish a robust anti-organized crime legal infrastructure: permissive laws and competent enforcers. Permissive laws allow law enforcement to target organized criminal entities as coherent groups. Competent enforcers are law enforcement bodies that are specialized in the investigation or prosecution of organized crime. I argue that such institutions are generally difficult to develop, as they inherently enhance the power of the national government. Anti-organized crime institutional development occurs when reformist leaders convince the public that organized crime poses a national, rather than a local, threat. This shift in public perception is necessary to put pressure on neutral and anti-reform decisionmakers to accept significant changes. Institutional development will be extended if the public’s sense of threat is maintained over time, which is most likely to occur when organized crime is portrayed as relatively cohesive. I conduct a plausibility probe of my theory regarding the onset of institutional reform on a sample of seven democratic nations which diverge on several theoretically significant dimensions. I find strong evidence of the mechanisms of the theory in a variety of different political and criminal contexts. I then conduct an in-depth comparative historical analysis of reform in Italy and the United States, both of which have developed particularly robust legal infrastructure to combat organized crime. I rely on a combination of archival, media, and interview data to closely trace the establishment of anti-organized crime legal institutions in these two countries. This dissertation makes three main contributions. First, it identifies an important outcome of interest, namely anti-organized crime legal institutions. Second, it combines the insights of comparative politics with legal analysis to explain the establishment of these institutions in democracies. Third, this project improves our understanding of the role of the state in the field of criminal politics. The domestic legal system is generally democratic states' first tool for repressing crime. By demonstrating how states develop their legal responses to such groups, this dissertation attempts to improve our understanding of the ways in which internal political forces may lead democratic governments to crack down on criminal organizations.