Advancing U.S. national interests depends increasingly on effective multilateral action. President Barack Obama has stressed the need to update international institutions to permit the collective management of emerging transnational problems and the peaceful accommodation of rising powers. The United Nations Security Council, the world's preeminent peace and security organ, should not be excluded from this vision to create a new global architecture of cooperation.The United States must lay out a longterm roadmap for the modest expansion of the Security Council, based on criteria commensurate with the obligations of Council membership. Stewart M. Patrick and Kara C. McDonald believe that by adopting a conditions-based, evolutionary approach, the U.S. government can shift the terms of a stymied debate and position itself as a leader on Council reform. In addition, aspirant countries would have the opportunity to prove their readiness to accept the burdens and responsibilities of defending world order. This would avoid the considerable risks of immediate Council enlargement, while giving these states an incentive to increase their contributions to global security.