Michael Barnett is Harold Stassen Chair at the Hubert H. Humphrey School and Adjunct Professor of Political Science at the University of Minnesota. He is the author of several books, including Eyewitness to a Genocide: The United Nations and Rwanda, and coeditor with Shibley Telhami of Identity and Foreign Policy in the Middle East (both from Cornell). He is also coeditor of Power and Global Governance. Martha Finnemore is Professor of Political Science and International Affairs at George Washington University. Her books The Purpose of Intervention: Changing Beliefs about the Use of Force and National Interests in International Society are also available from Cornell.