Twenty-first-century Europeans are suddenly confronting new choices about their place in the world. The most immediate challenges reflect tensions in the transatlantic partnership - long the keystone of European worldviews. In the Iraqi conflict President Bush posed a blunt general question to the world: 'Are you with us or against us?', and much of Europe chose the latter. More than at any time since 1945, Europeans are uncertain about the future of transatlantic cooperation. Internal European developments combine with this external shift to create the impression of a continental turning point. The fifty-year project of the European Union is entering a new phase. The Single Market program and monetary union realized the most ambitious visions of the EU's founding fathers. Most thinking about further integration is exceedingly vague. Simultaneous EU enlargement to the east (and beyond to Turkey) may create opportunities to reopen the Union's basic bargains. This book proposes to help students and scholars understand the many trends of change that have brought Europe to these crossroads. Its approach is novel in two ways. First, most similar scholarship either seeks a single grand theory of European change or implies that European politics is too complex to map change broadly. This book takes a middle-ground position, positing several distinct mechanisms of change and tracing them across policies and institutional settings. Second, it uses the United States as a reference point to chart European change. The aim is not comparative - the focus remains on Europe - but the volume maps out EU trends against American policy positions and institutional patterns, thus providing a useful comparative anchor for complex patterns. This is the seventh volume in the biennial series State of the European Union, launched in 1991, and produced under the auspices of the European Union Studies Association (EUSA).