In this grandly illuminating study of Asian and European regionalism, Katzenstein claims that world politics is built around regions that have been deeply influenced by the United States' postwar "imperium." Rich in themes and insights, the book provides a sort of sweeping archaeological account of the layers and complexities of postwar European and Asian territorial groupings. At the deepest level, these regions were given their distinctive shape by American power, global designs, and ties to Germany and Japan -- and the economic and security institutions that these allies built in the shadow of the Cold War. Both Asia and Europe exhibit what Katzenstein calls "porous regionalism," an openness that is reinforced by growth in cross-border exchanges and global transformations in interstate relations. The most interesting insights in the book come from the comparison between Asia's network style of open regionalism and Europe's more formal institutional complex. Some readers will be frustrated by the sheer complexity of the narrative. But this seems to be precisely Katzenstein's point: it is the convoluted interconnections of countries and regions that define the current global order.