One of the greatest challenges facing the United States today is the translation of its overwhelming might into effective influence. Traditionally, the United States has leveraged its power through bilateral and multilateral alliances. However, the end of the Cold War and the events of September 11, 2001, have led some policymakers and analysts to question the value of alliances in American foreign and defense policy. This monograph advocates that allies are more important than ever to the achievement of U.S. national security goals.