This dissertation examines how abuse-language and insults function in the plays of Plautus. Existing work on insults in Plautus is largely taxonomic, with small attention to the dynamics of insult among characters or to how insults are construed within the plays. Plautus is one of the most important Latin authors, and insult is a bedrock feature of his comic style. Moreover, every type of character in Plautus' plays-from slaves to gods-uses insult freely regardless of status and generic type, but characters do not all react to insults in the same way. Some will react calmly to extreme abuse, and others will become distraught over mild critique. This suggests that the "valence" of insult words is not stable; indeed, supposedly neutral or even positive terms can be insulting if used in certain situations. Moreover, Plautus' plays were designed to be realized through live, physical performance, and thus to understand the insult scenes they contain, we must consider not just the textual evidence of insult usage, but also how performance details-delivery, occasion, audience-also could have influenced or even altered surface meanings found in the text. Abuse scenes and their aftermath drive much of the dramatic action and humor in Plautus' plays; the various ways that participants in these scenes deploy and respond to insults are thus crucial evidence for in-text themes, as well as the social culture of 3rd- and 2nd-century Rome. To understand Plautus' comedy, we must also understand his insults.My project takes a "3D" view of insults in Plautus: I apply a theoretical method that combines performance theory and sociolinguistic theory-especially work on linguistic (im)politeness-to consider how insults function across and within social boundaries.� I place special emphasis on the idea that "social intimacy" is the defining factor for determining how potential insult meanings are resolved; how characters react to insult is the result of interpersonal relationships, and not of pure lexical semantics. Intimacy and rapport are major aspects of scripted character interactions, but they also can develop between audience and actors during the theatrical event, and this relationship ultimately mediates the semantic valence of insult terms.� I begin my study with a narrow analysis of a single, widespread insult (fur, "thief"), and then apply the generalized conclusions of that study to an analysis of multiple terms that occur in two-person scenes, with attention to how these affect (and are affected by) interpersonal relationships.� I then widen my scope and consider how the realities of ancient performance, as well as the perspective(s) of a heterogeneous audience, would have affected these relationships. Lastly, I consider how insults can become humorous, a development guided by the tension between two opposing modes of expression: one that produces pleasure, and the other pain. Between these, the dynamics of insult play out on a large scale in the arc of plot development.