The relationship between social status, behavioral characteristics, and central serotonergic function was examined in eight adult female cynomolgus monkeys (Mucuca fasciculuris). The subjects were housed in fourmember social groups for 6 months. Social behavior was observed three times a week. The early follicular phase of the menstrual cycle was determined based on the occurrence of menses, and the prolactin response to acute administration of fenfluramine HC1 during the early follicular phase was used as a measure of net brain serotonergic responsivity. Delta prolactin responses (the prolactin response to fenf luramine minus baseline concentrations) were lower in dominant than in subordinate females. Dominant females were more aggressive and less submissive than subordinates. Likewise, females with the lowest delta prolactin concentrations were more aggressive and less submissive than females that had relatively large increases in prolactin. Delta prolactin responses also correlated negatively with percent time eating and investigating in close proximity to penmates, and correlated positively with percent time scanning anxiously while alone. The same pattern of correlation was noted between social status and the aforementioned afiliative behaviors. It was concluded that high central serotonergic responsivity may be associated with low rates of aggression, high rates of submission, and subordinate social status in female cynomolgus monkeys.