Male rhesus monkeys (Macaca mulatta) 3 years of age were studied socially before and after ten weeks of confinement in a vertical-chamber apparatus designed to facilitate production of psychopathological disturbance. This study represents an initial effort to move beyond the use of young monkeys in a depression research program. Chamber confinement results in a significant increase in contact clinging between animals and a decrease in locomotion following removal from the apparatus. These behavior patterns are very atypical of laboratory-reared rhesus monkeys of this age and may represent a maturational regression induced by social means.