[From the Introduction]. The Iraq crisis has been a stress test for the transatlantic partners. It is the latest in a series that at once has been revealing and redefining their relationship since the Cold War’s end. The first Gulf War, Bosnia, Kosovo: each measured the ability of Americans and Europeans to continue working effectively together. Each highlighted distinctive habits of national mind and action obscured by the exigencies of the Cold War. Each raised pointed questions about the pattern of interaction between the United States and its major allies. Each provided insights into the capabilities, limitations, and internal stresses of multilateral organizations: NATO, the EU, the United Nations. Each altered attitudes and images in ways that affected how the next crisis was handled. The strains generated by Iraq II are more grievous, and the ramifications consequentially will be more far-reaching, for two reasons. The deviation from the normal modes of address was so extreme, and the divisions so acute, that the Alliance’s viability as the premier institution for Euro-American cooperation was called into question. Moreover, the crisis raised strategic issues of supreme importance so that differences could not be finessed. Either common ground will be found or the Alliance will founder. Current attempts at effecting a reconciliation quicken our interest in assessing Euro-American futures. The challenge is to define viable terms of a renewed partnership while seeking consensus on a security agenda dominated by a novel set of issues. A salutary first step is to take a searching look at assumptions that shape the present discourse.