The United States has been the dominant global power for over a quarter of a century, yet it has struggled to realize its lofty vision for a more peaceful and prosperous world. Relations with China and Russia have soured, the European Union is wobbling, and violent extremism continues to spread, all in the face of US efforts to maintain international stability. The reason, Stephen Walt argues, lies in America’s sense of omnipotence, which has encouraged successive administrations to pursue ambitious, risky, and often unnecessary foreign policy adventures. Is it time for the United States to develop a more restrained foreign policy outlook? Or would this only invite greater instability?