Anthony F. Lang's Agency and Ethics is an effort to reinterpret international intervention from a normative perspective, normative in this instance referring to activities that construct identities and provide policy guidance. Although he describes himself as a “realist” (p. 3), Lang sets out to explain the outcome of military intervention in terms of the interaction between the normative dimension and the “political,” which he defines as the competitive elements in a situation. He argues that states intervene in one another's affairs owing to what they believe are the norms that define their role(s) in international politics, and he shows how norms produce conflict as well as cooperation. In the cases that follow, Lang focuses on three norms—liberalism, colonialism, and humanitarianism: The first focuses on democracy, individual rights, and national self-determination; the second on responsibility for politically and economically less developed societies; and the third on assisting those in need. He ascribes the failure of intervention to normative disagreement among both friends and adversaries within and between participating countries, and he uses what Alexander George calls a “focused comparison” of cases to illustrate his claim.