Abstract
Four adult rhesus monkeys served as a nucleus for a group composed by successive addition of eight animals. More aggression resulted with this procedure than with simultaneous introduction of all animals. Severe fighting occurred when newcomers resisted attack. Resistance disappeared within 1200 seconds after release and further aggression and related responses decreased as newcomers were assimilated into the group. Frequency levels for selected activities approached the pattern of an established group two days after each animal was introduced, but some disturbance was still evident after one week.