Most of the cases involved rape. All cases were solved, and each case involved a perpetrator who was previously unknown to the victim. Eighty-one of the 210 offenders had carried out two or more attacks. Information was collected from the documentation compiled by police officers during their criminal investigations. The analysis considered each rape in terms of four behavioral domains: control, sex, escape, and style. Results revealed that the interaction of just 30 of the more than 150 original variables could be used to describe four distinct types of behavior in each of the four domains. In addition, 46 of the 50 offenders who had committed two or three rapes were consistent throughout their series within at least one of the domains. Similarly, 21 of the 31 offenders who had committed four or more rapes in their series were consistent throughout the series within at least one of the domains. Findings demonstrated that the methodology used can identify behavioral consistencies of the serial offenders in this database. The next phase of the research will attempt to validate the methodology in other, independent databases. Tables and list of other Police Research Group publications on serious crime