Moral philosophers have often appealed to claims about human nature or the nature of persons to defend or criticize various moral claims or theories. Though common, this methodology has received little systematic attention. This paper surveys a number of different ways that a moral theory could be said to "reflect" various facts about human nature or the nature of persons. It also examines various rationales for preferring (or even requiring) a moral theory to bear such reflecting relations to facts about us. It concludes with guarded optimism about the potential for this methodology to advance debate within moral theory.