Although the discipline of family law in the western legal tradition transcends the public/private law boundary in many ways, it is the argument of this Essay that family law, in the private law sense of defining the rights and obligations of members of a family, forms an important part of the legal architecture of nation-building in at least three ways. First, access to the resources of the nation-state devolves through biologically and culturally gendered national boundaries, both reflecting and reinforcing the differential status of men and women in the sphere of the family. Second, the social institution of the family and the legal framework that defines it embody power relations that, in turn, help to shape the larger polity. Hence, laws governing marriage, divorce, marital property, maintenance, child custody, child support, cohabitation, inheritance, and illegitimacy define not only power and status within families, but also within civil society, the market, and the political sphere. Third, the symbolic family, and sometimes the law defining it, may figure in important ways in the struggle for national identity that often takes place contemporaneously with nation-building. In Part II of this Essay, we explore the first claim, that national boundaries are gendered through the use of family relationships to control access to citizenship and thus to the resources and the protection of the state. We suggest that the use of kinship ties in an explicitly gendered way in the United States reinforces a concept of ethnic nationalism, casting women, and especially mothers, as the symbolic protectors of national identity. In Part III, we analyze ways in which family structure is defined by and reinforces hierarchy within the larger society. Following an exploration of theoretical arguments concerning the interplay of family and social hierarchy, we offer as an example of this dynamic the historical manipulation of African customary law by colonial powers. Finally, in Part IV, we argue that the ideology of the family often figures in important ways in the development of national identity in post-colonial or post-crisis states. We then discuss the example of South Africa and show how family law can serve as a site for the intersection of nationalist politics and the legal architecture of the nation-building process, here again in ways that are highly gendered.