Tyrrell, a distinguished Australian historian, has written a rich intellectual history of the dramatic shifts in the meaning of the defining but, it turns out, highly malleable idea of “American exceptionalism,” from its roots in the revolutionary era to the present. Tracing the term’s changing significance illuminates U.S. history more broadly. At times, this exceptionalism’s principal substance has been political; at other times, religious; and at yet other times (although this has been poorly appreciated), it has rested primarily on the country’s material abundance, whether of its rich natural endowment or its bountiful consumer society. Often, American exceptionalism seemed to denote only that the United States was uniquely great in its wealth and power. But in the beginning, when the fledgling country was neither wealthy nor powerful, exceptionalism was nonetheless a strongly held “loose and grassroots feeling” that the new country was a major political innovation, destined to be a model for others. After numerous manifestations in the intervening years, American exceptionalism has emerged in the past dozen years as a “state-sponsored ideology,” a full-throated “ism” seen in some quarters as an accurate litmus test of patriotism. Closely related but distinct concepts, including “the American way of life” (framing American identity in opposition to communism), “the American dream” (the opportunity for all people to achieve everything their ability and ambition allow), and “the American creed” (capturing the political values of individualism and egalitarianism), provide additional insights. A tough closing chapter examines the often gaping differences between the beliefs Americans hold regarding their country’s exceptionalism and the realities of life in the United States and American conduct abroad.