Population policy has taken two divergent trajectories. In the developing part of the world, controlling population growth has been a major tune of the debate more than a half-century ago. In the more developed part of the world, an inverse pattern results in the discussion over the facilitation of population growth. The ethical debates on population policy have primarily focused on the former and ignored the latter. This paper proposes a more comprehensive account that justifies states’ population policy interventions. We (...) first consider the reasons that support pro-natalist policies to enhance fertility rates and argue that these policies are ethically problematic. We then establish an ethics of population policy grounded on account of self-sustaining the body politic, which consists of four criteria: survival, replacement, accountability, and solidarity. We discuss the implications of this account regarding birth-control and pro-natalist policies, as well as non-procreative policies such as immigration, adoption, and unintended baby-saving strategies. (shrink)