Abstract 10.1002/zoo.1430080514.abs This paper reviews literature on the relation between captive environments and social behavior, particularly aggressive behavior, in monkeys and apes. The conclusion is that theories of “crowding” and “stress” are too simplistic to account for the observed relation. Instead, it is suggested that environmental effects be investigated from the standpoint of behavioral adjustment. Primates show behavior patterns that seem to aim at the avoidance of conflict and the reduction of social tensions. Such coping mechanisms are expected to be especially effective in groups that have lived in a particular environment for a long time. As an indication that this may be so, data on stable groups of rhesus monkeys under three very different conditions show a remarkable similarity in aggression rate.