In an international system that lacks centralized authority, the burden of enforcing the law generally falls on individual states. In many areas of transnational enforcement such as financial fraud, cybercrime, and tax evasion, the United States has historically assumed a prominent leadership role. In recent years, other states have also expanded their enforcement capabilities and activities. This Article proposes a theoretical framework to understand transnational enforcement leadership, drawing on theories of global public goods (GPGs) and leadership from economics and political science. Because transnational enforcement often has the attributes of a GPG, it tends to be systematically underprovided. States that possess greater resources and can capture more of the benefits tend to become leaders, thus closing part of the gap. Leaders can also derive significant private benefits by extracting penalties from their targets and entrenching their own laws as global standards. In addition, they benefit from cost advantages derived from existing enforcement capabilities, control over transnational hubs, and economies of scale. This self-reinforcing dynamic generates the “World Police Paradox:” leadership enhances global welfare, but it often takes the form of unilateral action and bestows upon leaders a privileged role in the international system. The Article acknowledges these concerns but argues that, given obstacles to effective international cooperation, leadership may often be the attainable second-best outcome. In addition, there is no sharp dichotomy between leadership and cooperation. Leadership can sometimes unlock the possibility of cooperation, as illustrated by the examples of bribery and tax evasion. A leader also cannot act despotically: its need for assistance by other states, and their ability to respond to perceived excesses, constrain its actions. Finally, the Article argues that many features of transnational enforcement leadership also apply to state-to-state enforcement and can illuminate the role of powerful states in sustaining international legal regimes.