International relations features different types of scholarship. These types are metaphor, history, theory, engineering, and pattern recognition. This essay discusses the nature and contribution of each type as research characteristic of these different undertakings shows substantial overtime continuity in attracting varying attention from identifiable communities. It also raises several concerns about the extant literature. These concerns address the problems of endogeneity, selection effects, concept stretching, over-determination and indeterminacy, multiple conjunctural causality, and falsifiable proposition. Although hardly representing novel discoveries, they present generic and seemingly persistent challenges to valid inference. While not irrelevant to the conduct of social inquiry in general, this review addresses specifically international relations scholarship.