The behavioral repertoire of 18 captive, groupliving, talapoin monkeys is described. Postures, body gestures, and noises provide their most important signals. Facial gestures are used rarely. Ganging-up, chaining of aggression, and aggression during courtship are more frequent among talapoins than among other monkeys. Activities of individuals are synchronized. The behavior of this species is more similar to that of Cercopithecus monkeys than to that of other Old World monkeys.