Thesis advisor: James Cronin / Thesis advisor: Devin O. Pendas / All efforts after the First World War to found — or reform — government on a democratic basis embraced the abstract concept that democratic legitimacy derived from the consent of the people. In this new age of national self-determination, however, the practical predicament became defining who constituted “the people” and how minorities would be managed. While historians have analyzed this issue in the “new” states of central and eastern Europe, this dissertation argues that it also plagued the supposedly more mature democracies of the Western European victors — Britain, France, and Italy. An analysis of the domestic population policies of those victors demonstrates that a new conception of democracy — based on both liberalism and nationalism — led them to pursue illiberal policies of population engineering with, paradoxically, the best of intentions: the preservation and stability of democracy itself. In an era in which people were becoming more involved in choosing their governments, governments were becoming more involved in choosing their people. While the victors sought to craft a more ethical — or at least more legalistic — form of population engineering than the often violent and ad hoc versions employed further east, the result nevertheless remained at odds with the ethical foundations of liberal democracy. / Thesis (PhD) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: History.