The results were analyzed to determine if patterns of similarity exist that characterize the acts of specific offenders and to determine if there is a relationship between the similarity of offenses and the likelihood of repeated offenses. The findings support the hypothesis that sexual offenses committed by the same offender were more similar than those committed by different offenders. In this group of offenders, patterns of offending, once established, remained quite stable. Offenders who were more aggressive tended to be so across all of their offenses, while less aggressive offenders tended to remain less aggressive, but continued to pursue the same victim for additional sexual acts. Within each of these two categories, individual offenders adopted unique and identifiable subordinate patterns. The results suggest that it may be possible to determine the probability that a particular offense was committed by a particular offender. Furthermore, similarity between offenses may be a useful indicator of the offender's future dangerousness. 1 table and 7 references