This dissertation attempts to explain why cross-national variation exists in government approaches to dealing with illegal drugs. As other scholars have shown, several domestic and international political factors do account for some of this variance. However less is known of the effect that bureaucratic dominance and political institutions may have on drug policy. This research argues that bureaucrats define problems in ways that make their services the best possible solution to policymakers. Mediating the ability of bureaucrats to influence drug policy outcomes are political institutions. Certain institutional structures foster a competitive policymaking environment while others foster a more cooperative policymaking environment. In the former of these, law enforcement approaches to the drug problem are often retained as the status quo because competition between policy actors prevents consideration of alternatives. In the latter environment however, prevention, treatment, and harm reduction approaches to the drug problem are developed because cooperation between policymakers allows other actors. namely public health bureaucrats.to influence drug policy decision making. To test this argument, I constructed an original dataset that includes over 4,000 observations of drug policy in 101 democracies. Institutional data on intergovernmental relations, regime type, political bargaining, electoral design, and cameralism were regressed on 6 different drug policy indices: law enforcement, deterrence-based prevention, abstinence-based treatment, educationbased prevention, substitution-based treatment, and harm reduction. While controlling for government resource capacity, severity of the drug problem, international pressure, and political ideology, I found that institutions explain a portion of the variance in drug policy outcomes. Providing in-depth information about these phenomena is a large amount of field data I collected while interviewing 155 politicians, bureaucrats, interest group leaders, and service providers. Respondents from all four of the case countries examined in this research.including United States, Canada, Austria, and Netherlands.report that bureaucrats play a major role in the formation of drug policy. Which bureaucrats have the most influence on policymakers is largely a function of domestic political conditions, international political factors, and political institutions.