Identity has emerged gradually within contemporary debates in social science and has led to vivid debates in International Relations. The aim of this article is to show how identity, or identity-oriented approach, may affect fundamental theoretical concepts of IR. At first the importance of identity in theoretical and meta-theoretical debates in IR is discussed. Then identity itself is conceptualized. On the basis of a distinction made between political and normative impacts of identity, the next two sections examine the ways in which they have influenced changes in theoretical concepts such as power, security, sovereignty and diplomacy as well as normative ones such as human rights and ethics.