This prodigiously researched volume examines a group of maverick senators, including William Borah, Robert La Follette, and many lesser lights, who developed an acerbic critique of American foreign policy from the First World War to the 1930s. Generally opposed to a military buildup before the war and keen on disarmament in the 1920s, they championed self-determination for colonized peoples and normally condemned U.S. interventions in the western hemisphere. They hated the League of Nations in part because it required cooperation with the paragons of Old World diplomacy. At pains to show that the peace progressives had a coherent outlook, Johnson calls their perspective a left-wing alternative to Wilsonianism and the "business internationalism" of 1920s Republicans. But these great naysayers drew also on conservative traditions, which helps explain the striking resemblance between the peace progressives and today's paleoconservatives.