This thesis is a critical examination of civic nationalism that focuses on the disconnect between nationalist ideology and the social bases of nationhood, and the implications that this disconnect has for the feasibility of civic nationalism as a policy prescription for issues such as intra-state nationalist conflict and immigrant integration. While problems with the principles of civic nationalist ideology are important, my focus here is the more significant problem that civic nationalism is based on a general theory of nations and nationalism that treats them as solely ideological phenomena. Against this I argue that the term ‘nationalism’ refers to several different phenomena, most importantly a ‘system of culture’ or way of organizing society as described by Ernest Gellner and Benedict Anderson, and that augmenting Gellner and Anderson’s theories with the kind of relational social theory used by authors such as Rogers Brubaker and Charles Tilly provides an alternative explanation that is a better match for the evidence. If this is the case, I contend, then civic nationalism is both a misrepresentation of the history of nations and nationalism and infeasible as a prescription for policy issues such as intra-state nationalist conflict and immigrant integration. These arguments are supported with empirical evidence that is principally drawn from four cases: France, the United States, Northern Ireland, and Canada.