Moral psychology is both old and new. Old because moral thought has long been a central focus of theology and philosophy. Indeed, many of the theories that we explore today were proposed first by scholars such as Aristotle, Kant, and Hume. Young because the scientific study of morality—and, specifically, the study of what goes on in a person’s head when making a moral judgment—has been a topic of serious inquiry only over the last couple of decades. Even now, it is just barely mainstream. This chapter is itself a combination of the old and the new. I am going to consider two broad questions that would have been entirely familiar to philosophers such as Aristotle, but are also the topic of considerable contemporary research and theorizing: (1) What is our natural human moral endowment? (2) To what extent are moral judgments the products of our emotions? I will have the most to say about the first question, and will review a body of empirical work that bears on it; much of this research is still in progress. The answer to the second question will be briefer and more tentative, and will draw in part upon this empirical work. Many leading researchers, including other contributors to this volume, have their own answers to these questions, and at every point in this chapter, I will do my best to make contact