Institutional rules--procedural, structural, and normative--are held to play important roles in affecting strategies and outcomes. Their influence is widely recognized in domestic politics, but their role in international politics remains relatively underdeveloped. In this close examination of how institutional rules have affected the relative influence and power of members of the Organization of American States, Shaw demonstrates the importance of rules where they are often considered to be least effective: shaping the behavior of a hegemon, the United States. Four factors are considered important in analyzing the effects of institutional rules: the level of consensus among Latin American members, the extent of threat to regional stability, the amount of resources needed to address an issue, and the reliance on norms, including non-intervention and state sovereignty. Tracing their interaction, Shaw finds that the rules affected state and organizational decisions in the highly germane area of conflict resolution. By demonstrating the importance of organizational rules where they might be expected to be least effective, this is an important contribution to the study of international relations.