The Greek comic poet Aristophanes often comments on the value of different comic modes. When he articulates his own comic preferences, his “poetics,” he does so using the framework of a dichotomy that contrasts a low-comic mode and a high-comic mode. The low mode is characterized by stock characters and routines, physical humor, obscenity, and a sense of antiquity. The high-comic mode is politically engaged, didactic, sophisticated, novel, and concerned with contemporary events. Aristophanes consistently speaks of the low-comic mode in negative terms. He frequently accuses his rivals of producing low comedy and claims that he would never stoop to such frivolity himself. His own comedy, he claims, is always produced in the high mode. Herein lies the problem of Aristophanic poetics: Aristophanes makes extensive use of all the low comic routines that he disparages so vehemently. This irony has long been noted by scholars but it is usually claimed that Aristophanes includes low comedy as a concession to the uneducated masses in his audience. I argue rather that Aristophanes’ ironic disavowal of the low serves paradoxically to emphasize its necessity for the comic genre. In part one I analyze the concept of low comedy by considering the evidence in Aristophanes’ plays (chapter one) and in the fragments of Sicilian and fifth-century Athenian comedy, testimonia, scholia, and vase paintings (chapter two). This analysis results in a much broader understanding than previous scholarship has offered of the types of humor that could be classed as low comedy. In chapter three I tackle Aristophanes’ definition of the high-comic mode. I identify two distinct modes that Aristophanes opposes to the low: the political mode (angry, aggressive, didactic, offers advice to the city) and the intellectual mode (restrained, verbal, includes parody of tragedy and philosophy). Despite clear differences between these two modes, Aristophanes often comically conflates them, destabilizing his claim to be a high-comic poet. In part two I analyze how the low-high dichotomy functions in Wasps (chapter four), Lysistrata and Thesmophoriazusae (chapter five), and Frogs (chapter six). In each case I demonstrate that the comedies metatheatrically enact the dichotomy revealing the necessity of low comedy as a foundational element of the comic genre. Unlike his low-comic rivals, however, Aristophanes imbues the low-comic mode with novelty, contemporary relevance, and sophistication, resulting in a dual low-high poetics.