Since the end of the Cold War, scholars have debated the merits of the major theoretical traditions in international relations and foreign policy. Neorealism was criticized for failing to predict the end of bipolarity in material capabilities. Constructivism emerged during this time as a viable alternative explanation for the Cold War based on the role of ideas. This paper seeks to assess the impact of material and ideational factors on the origin, development, and end of the Cold War through an examination of the roles adopted by U.S. Presidents in their foreign policy doctrines. The paper finds that the origin of the Cold War was primarily ideational and was constituted by the “roles of bipolarity” adopted in the Truman Doctrine. During the Cold War, minor variations in these roles can be explained by shifts in material capabilities. The end of the Cold War was the result of changes in Soviet ideas, which were later confirmed by the collapse of the Soviet Union. After the end of bipolarity, we see the United States struggling to identify its proper foreign policy role.