This article reviews the key role that case study methods have played in the study of international relations in the United States. Case studies in the International Relations subfield are not the unconnected, atheoretical, and idiographic studies that their critics decry. International Relations case studies follow an increasingly standardized and rigorous set of prescriptions and have, together with statistical and formal work, contributed to cumulatively improving understandings of world politics. The article discusses and reviews examples of case selection criteria (including least likely, least and most similar, and deviant cases); conceptual innovation; typological theories, explanatory typologies, qualitative comparative analysis, an...