Recent developments in ethology and animal ethics have put pressure on the view that nonhuman animals should be described as moral patients, namely, as beings towards whom we have obligations but cannot owe duties to others. Within the debate on animal morality, some authors, and most influentially, philosopher Christine Korgsaard, have argued that animals cannot be moral agents because they lack normative self-government. This article poses an empirical challenge to Korsgaard’s account of moral agency by shedding light on the literature on human beings’ moral development. In this paper, I examine three possible strategies that Kantians like Korsgaard could use to make sense of children’s and teenagers’ moral capacities: (1) accept that most younger children who are incapable of normative self-government could be moral agents, (2) admit that older children and teenagers can be moral agents, or (3) deny altogether than children and teenagers can be moral agents. However, I argue that these three strategies are unsuccessful. As concluding remarks, I also highlight how gradualist and multi-faceted accounts of moral agency can better make sense of the puzzling case of children’s and teenagers’ moral capacities.