AbstractSocial prediction was used to examine the causal role of physiological arousal in self‐ evaluation maintenance (SEM) processes. Subjects' level of arousal was manipulated by having half of the subjects engage in physical exercise and half of the subjects relax prior to receiving performance feedback on high and low relevance tasks. On each task, subjects were given an opportunity to predict the performance of a friend or a stranger. The SEM modelpredicts that the more relevant the task the less charitable one's perception of another S performance, particularly a close other. Subjects in the high arousal condition showed a pattern of behaviour which was significantly closer to that predicted by the SEM model than subjects in the low arousal condition. Thus arousal appears to play a causal role in the unfolding of SEM behavrour