This article traces and explains how U.S. policy officials and IR scholars have conceived of the relationship between economics and security over the past half-century. During the interwar years, economics and security were integrated in both scholarship and statecraft. During the Cold War, scholars treated the two issues as separate areas of inquiry. U.S. policymakers integrated economics and security during the early Cold War, but by the 1970s the two components of U.S. foreign policy had drifted apart. After the Cold War, a renewed emphasis has emerged in both U.S. statecraft and IR scholarship on the integration of economics and security. Three factors explain these patterns: (1) the international distribution of material capabilities, (2) perceptions of the strategic environment, and (3) perceptions of the position of the United States in international economic competition.