The United States was thrust so suddenly into the war on terrorism that it was forced to deal with both immediate operational issues and broad strategic questions simultaneously. Even while the American military is consolidating battlefield success in Afghanistan, strategic thinkers and leaders are developing a long-term strategy. In this process, nothing is more important than defining victory. In this monograph, Dr. Colin Gray, one of the world’s leading strategic thinkers, explores the concept of victory in the war in terrorism, but he does so by placing it within the larger currents of change that are sweeping the global security environment. He contends that the time-tested idea of decisive victory is still an important one, but must be designed very carefully in this dangerous new world. To do so correctly can provide the foundation for an effective strategy. To fail to do so could be the first step toward strategic defeat.