AbstractSeveral tests failed to detect any relationship between the amount of self‐aggression (SA) and either spontaneous or contrived dominance rank of self‐aggressive stumptailed macaques living in groups. SA and stereotyped movements were affected differently when the subjects were given drugs, suggesting a dissociation between these two behaviors. SA did not correlate with measured adrenocortical arousal, indicating that self‐aggressive monkeys are not stressed as they are when receiving social aggression. Theories of social aggression, such as social learning theory, deal poorly with self‐directed agg