This fine study purports to offer “a normative theory of nationalism.” Such a theory is needed, the author claims, because most of the literature on the ethics of secession proceeds on the mistaken assumption that the normative problem of state breakup is best addressed by applying established liberal arguments or values to the issue at hand. In fact, however, it makes little sense to derive a theory of secession in this way, rather than by considering directly the kinds of normative claims secessionists make. These are nationalist claims. We need, moreover, to recognize that well-known accounts of nationalism, such as those offered by Ernest Gellner, for whom nationalism is a political principle that holds that the political and national unit should be congruent, are inadequate—either because they include too much, or because, as in the case of Gellner (Nations and Nationalism, 1983), they associate it with a particular set of demands or principles. Nationalism, according to Margaret Moore, should be understood as “a normative argument that confers moral value on national membership, and on the past and future existence of the nation, and identifies the nation with a particular homeland or part of the globe” (p. 5). Once we have understood this, we will be in a better position to understand the key policies and demands of nationalists, including their occasional (and only occasional) demands for national self-determination, and to understand the normative limits of nationalism. And we will then be in a better position to understand the nature, and defensibility, of national self-determination, and of secession in particular.