This paper compares Aquinas’ account of the fundamental evaluative notions of good and bad with the theories of normativity offered by the philosophers Christine Korsgaard and T. M. Scanlon. This paper was initially motivated by the observation that Korsgaard and Scanlon each share a point of contact with Aquinas’ thought, even though their views on normativity are very different from one another, and from Aquinas’ own views. Korsgaard’s approach to normativity shares at least one feature with Aquinas’ moral theory, namely, an acknowledgment of the normativity of nature, correctly understood. Scanlon does not have any such commitment, but he does offer an account of the fundamental status of reasons which is suggestively similar to Aquinas’ claim that practical reason depends on first principles. The upshot is that Aquinas seems to agree with some significant aspect of two distinct theories of normativity, whose proponents disagree with each other in fundamental ways. And this raises a question – what is it about Aquinas’ understanding of normativity, as we would put it, which allows him to hold together seemingly incompatible approaches in this way? This paper offers an answer to this question.