This chapter provides an account of Plato’s understanding of “the laughable” (to geloion), the closest ancient Greek concept to “humor.” It has two mains aims. The first is to understand how Plato’s primarily negative theoretical reflections on humor, laughter, and comedy can be made consistent with the veritable treasure trove of humor within Plato’s dialogues. Plato’s theory details the harms and dangers of laughter and comedy, but Plato’s writing employs a variety of comedic techniques. How is this possible? In short, I argue that while Plato does think that a large majority of the things that people actually laugh at are ethically harmful, he also thinks that an ethically defensible form of humor aims at moral improvement by targeting and exposing self-ignorance, which the Philebus holds is truly laughable. It is this latter kind of humor that Plato employs in his dialogues. The chapter’s second aim is to situate Plato’s account of the laughable in the context of contemporary theories of humor. While Plato is often considered to be a forerunner of superiority theories, I argue that we can also find seeds of incongruity theory and psychological release theories of humor. However, Plato significantly departs from modern theories, because he is mainly interested in outlining a normative rather than descriptive notion of the laughable, in what we ought to laugh at rather than in what we actually laugh at. Some readers may be inclined to dismiss Plato’s moralizing as inappropriate to the topic, but if one thinks, for example, that one should not either make or laugh at racist jokes, then a normative theory can help to explain why.