Experimental moral philosophy emerged as a methodology in the last decade of the twentieth century, as a branch of the larger experimental philosophy (X-Phi) approach. Experimental moral philosophy is the empirical study of moral intuitions, judgments, and behaviors. Like other forms of experimental philosophy, it involves gathering data using experimental methods and using these data to substantiate, undermine, or revise philosophical theories. In this case, the theories in question concern the nature of moral reasoning and judgment; the extent and sources of moral obligations; the nature of a good person and a good life; even the scope and nature of moral theory itself. This entry begins with a brief look at the historical uses of empirical data in moral theory and goes on to ask what, if anything, is distinctive about experimental moral philosophy—how should we distinguish it from related work in empirical moral psychology? After discussing some strategies for answering this question, the entry examines two of the main projects within experimental moral philosophy, and then discusses some of the most prominent areas of research within the field. As we will see, in some cases experimental moral philosophy has opened up new avenues of investigation, while in other cases it has influenced longstanding debates within moral theory.