Pygmy chimpanzees or bonobos (Pan paniscus) have become best known for their varied and extensive repertoire of sexual behaviors and their use of sex in nonreproductive situations (Kano, 1986/1992; Furuichi, 1987; Hashimoto & Furuichi, 1994; de Waal, 1995; de Waal & Lanting, 1997). They are also quite adept at communicating their intentions and coordinating social activities, and many of these behaviors are closely linked to their highly cohesive social structure. In the wild, female genital–genital rubbing serves as a greeting among well-known individuals, as well as to form social bonds among unrelated individuals and ease tensions when entering a potentially competitive situation such as a fruit tree. Variations on a rocking gesture are used to request different kinds of close contact between individuals, ranging from close sitting to copulation (Kuroda, 1984; Ingmanson, 1992). Branch dragging is used to organize and direct group travel (Ingmanson, 1988, 1996), and play behavior is often signaled by carrying an object (Ingmanson, 1996). In captive studies, communication is also used to organize social activities – zoo bonobos use a clapping gesture to initiate grooming in a social group (Ingmanson, 1987, 1998) and have an extensive range of reconciliation behaviors (de Waal, 1989). Symbol-trained bonobos use lexicons on a keyboard to communicate both social and nonsocial desires, and respond appropriately to others' keyboard communications (Savage-Rumbaugh, 1984; Greenfield & Savage-Rumbaugh, 1993; Savage-Rumbaugh & Lewin, 1994). All of these behaviors coordinate social activities and reduce tension in the group by avoiding misunderstandings, thereby reducing aggression.