Practical rationality is, inter alia, a disposition to reason well about one’s actions. This dissertation develops a neo-Aristotelian account of practical rationality by considering what such a disposition must be like. Accordingly, it begins with a treatment of the nature of reasoning. Recent treatments of reasoning have distorted what it is to reason well, since they treat reasoning as a process that conforms, or ought to conform, to rules of reasoning. To the contrary, I defend the Aristotelian idea that reasoning is a species of inquiry. As a species of inquiry, reasoning proceeds ad hoc, by way of the reasoner’s remembering and noticing what is salient for the addressing of some question. What conforms to rules is not the process of reasoning but rather the rationale on the basis of which the reasoner responds to her question. In the remainder of the dissertation, I provide an account of such rationales, that is, of the structure of practical justification, by developing a form of neo-Aristotelian ethical naturalism indebted to the later work of Philippa Foot. On a properly conceived naturalism, I argue, virtuous agents are moved not by facts about human nature but by salient features of their situations, and indeed they come to know human nature only from the inside, in the experience of virtuous motivation.