Recent years have seen the so-called New Left school of historiography cut a wide swath through the study of American diplomacy. Reacting at least in part to the exigencies of the Vietnam War, as well as to older schools of diplomatic history, its adherents have molded a point of view that has emphasized economic factors as the driving force in American foreign policy. In this essay. Dr. Braeman focuses on the 1920s, a crucial decade in New Left thinking. After probing the intellectual origins of this school of thought, he brings historical statistics to bear in his analysis of American investment abroad, the conduct of American policymakers, and the contending interpretations of American foreign policy.