This study investigates humor by mediators and disputants in 95 civil case mediations. Consistent with the majority of the humor literature, as well as with the descriptive and prescriptive literature on mediation, we found that some humor was used by mediators and disputants in a “nice” and affiliative way, to control tension and to facilitate amicable relationships. Some of that humor also came in the form of reciprocal back-and-forth banter or in a positive and affiliative form that was unrelated to the mediation itself. However, many incidents of humor were harsh, as well as aggressive, and that humor often served specific functions within the mediation context. Mediators, and, to a lesser extent, disputants, used humor as a means of applying pressure to another party. Disputants, but seldom mediators, used humor defensively, to counter the pressure applied to them. We discuss how our results stand in contrast to the conventional wisdom about humor; we extend humor and conflict theory by integrating theory and perspectives on power; and we explain how our findings might extend to various social situations that involve power differentials between parties.