The identity problematique is fast moving to the core of the research agenda of international relations discipline, and the concept of state identity has now become a permanent feature of the constructivist discourse. This paper identifies four problems attendant upon the introduction of the state identity con-cept to international relations theory. Firstly, the relationship between state identity and other importantconcepts of constructivist argument is underspecified. Secondly, the question of how states chooseamong multiple identities is not sufficiently addressed by constructivists. Thirdly, the concept of stateidentity has been rather slow to find its way into empirical research and is still largely ignored by therationalist scholars. Finally, the link between state identities and power tends to be neglected by bothconstructivist scholars and their rationalist rivals. In addressing these problems, the paper clarifies therelationship between state identity, culture and norms and provides a systematic review of the state iden-tity approaches. The paper proposes a new definition of the concept that is compatible with the rational-ist foundations of the mainstream of international relations discipline. It illuminates the role of stateidentity as a tool in the strategic interaction among states, and provides several examples to illustrate theclose relationship between state identities and power. Since power is the key explanatory concept formany rationalist approaches, the paper argues that the concept of state identity also deserves to be animportant part of rationalist analytical frameworks.