This article makes a case in defense of oral history in the study of political science and international relations. The existing literature has scrutinized the technical aspects and appropriate use of oral material. This article focuses on the circumstances under which oral history may be an indispensable method of scholarly investigation: first, when written primary sources are not readily available; second, when an investigation targets complex and secret high-level negotiations; and third, when the main research concern is the human agent’s perspective and ideational factors. The article first addresses the issue of reliability and rigor of oral history as compared to written sources and then concentrates on the creation of Mercosur as an example of the validity of oral history under the three circumstances identified. The conclusion proposes a revival of a more historical approach to political studies.