This book shows that identity studies in the discipline of International Relations (IR) generally cohere around two discrete understandings of being, substantialism and correlationism, and that their analytical, theoretical, and epistemological orientations are split along those lines. This binary opposition makes it difficult for identity scholarship to meet the internal validity standard of coherence while unnecessarily narrowing the theoretical lenses of constructivism in IR. The author argues that the best way to step outside that binary is to re-ground identity in ontology of immanence. The book shows that immanent ontological thinking enables us to have a pluralist epistemology and methodology for the study of identity, including both positivist and interpretivist orientations, without yielding a logically inconsistent alignment.