This article argues that Hobbes was actively engaged in the debates about population size as a component of his broader approach to political economy. By the seventeenth century, beliefs about economic well-being routinely turned back onto the question of population size. This article situates Hobbes's arguments about populations in and among the common arguments for the movement of people in the seventeenth century. Hobbes rejected the natural law tradition of hospitality, which required that states take care of foreigners, and populationist arguments, which assumed that economic progress was predicated on rapid population growth. Specifically, this article will show that Hobbes held a view common to the late Tudor period; namely, a wise sovereign should be actively engaged in regulating population inflows and outflows. Not only did this require careful management of domestic procreative policies, but it also had implications for colonization and war-making.