Although powerful states have the ability to dominate the international system to achieve their policy preferences, such dominance has limits in the Organization of American States. Even though the United States, its most powerful member state, has considerable influence over OAS actions, institutional factors also affect decisionmaking and produce more varied outcomes than one might anticipate. Adapting three different perspectives from organizational sociology, this study constructs an analytical framework to explore the impact of structural, normative, internal relational, and environmental factors on the level of U.S. influence in the OAS. Four hypotheses are tested on 30 cases of regional conflict management from 1948 to 2002. The organizational variables also reveal incentives for the United States to act multilaterally rather than unilaterally in most instances in the post-Cold War era.