This study had two aims. Firstly, it examined the similarity between subjects' ratings of themselves and others and their scores on various personality tests. A group of 264 undergraduates in psychology completed Self-Monitoring Scale and the Neuroticism and Extraversion Scales from the Eysenck Personality Questionnaire . Then, they estimated both their own score and that of a peer on those questionnaires. The results showed that subjects (i) were jairly good at estimating their own and others' extraversion and neuroticism scores, (ii) were less accurate at estimating self-monitoring scores, (iii) were better at predicting their own scores than those of others, and (iv) erroneously believed themselves to be significantly similar to the chosen peer. Secondly, individual differences in the accuracy of personality estimation were studied. According to Synder's (1974) self-monitoring construct, people high in self-monitoring would be especially adept at reading others' expressive behaviours; therefore, any differences in the accuracy of perceiving the personality of others might be associated with differences in self-monitoring. High selfmonitors were more accurate thun low self-monitors at estimating neuroticism scores for others. Another implication of the self-monitoring theory is that, taking high and low self-monitors as targets of others' estimations, there should be greater discrepancy between actual scores and peer estimations for high self-monitors. The results here supported this prediction, but only in self-monitoring estimation.