We report on findings from a study into differences in personality and background characteristics between juvenile sex offenders who commit their sex offenses on their own and those who do so in a group. Solo offenders were found to score significantly higher on neuroticism, impulsivity and sensation seeking, but scored lower on sociability. In addition, the solo offenders in the sample were more often recidivists for sexual offenses, and were more often themselves a victim of a sexual offense. Solo offenders were significantly older than juveniles who had committed a sexual offense with a group. On the basis of these results we recommend differential treatment for the two types of offenders.