This well-researched and stimulating book makes an important addition to the growing literature that interprets U.S. foreign policy from a historical perspective. Although his account ends with the United States' entry into World War II, Hendrickson seeks to demonstrate the relevance of what came before the war to what came next -- in the Cold War and beyond. He argues, convincingly, that the ideas Americans used to understand the twentieth-century world had a long history in domestic political debate. Hendrickson's greatest contribution is to use the recurring debates over the nature of the union to examine American ideas about the broader international system. It was the depth and sophistication of Americans' understanding of relations between the American states, Hendrickson argues, that prepared the United States for its global role post-1945. There are problems with the argument, and not everyone will agree that the facts fit his framework as tightly as he maintains; overall, however, Hendrickson has written a book that no serious student of the United States' political tradition can afford to ignore.