Abstract
No state can fully achieve its objectives without the authority and material support which international institutions alone can provide. The US espouses multilateralism as a virtue and, like every other state, seeks to use multilateral institutions as instruments for achieving its own policies. However, America's relations with such institutions are complicated by four, sometimes competing roles which the US plays in the international system: a prophetic and reformist role; an infra-organisational role; a custodial role; and a domestic-pressure reactive role. Occasionally all four roles are performed harmoniously, but in particular cases they may lead the US to conduct its international institutional diplomacy more abrasively than intended. The probable future is one in which the US remains paramount in the world and, because of its character and the multiplicity of its roles, continues to stir controversy in its complex relationships with international institutions.