This study obtained scores on the Self-Reported Delinquency Scale (Mak, 1993) from 131 adolescents (72 females and 59 males). Seriousness judgments for each of the items on the scale were obtained from 13 police officers, 14 teachers, 12 lawyers, and 15 psychology students. These judgments were used to derive seriousness scores for each adolescent participant, and several strategies were evaluated for distinguishing serious from minor offending. The results show that the raters judged different categories of offenses to be differentially serious, with crimes against the person being deemed as most serious. Incorporating only the "most serious" offenses was identified as more useful than using the range of offenses in order to distinguish serious from minor offenders. Acknowledging the difficulties involved in choosing an optimal classification system, the authors propose that self-report measures for juvenile crime or delinquency ought to incorporate an index for distinguishing serious from minor offenders. Distinguishing levels of offending seriousness could prove useful for identifying those adolescents who are most at-risk for continuing involvement in crime. 2 tables and 27 references