Participants consisted of all youth served by a public mental health (MH) agency or the juvenile justice system between April 1995 and June 1998 in Sonoma County. During this period, 3,367 juveniles received public MH services; and of these, 684 (20 percent) were arrested during the study period. Of all the juveniles arrested in the county, 31 percent had some history with the public MH system. Of all juveniles arrested in the county during the study period, MH service users had more arrests than juveniles who had not received MH services. The types of crimes committed by both groups were misdemeanors. A subsample of 94 MH service users with arrests was matched on demographics with 94 juvenile MH service users without any arrests. MH users with arrests had a higher frequency of conduct disorder, higher Child Behavior Checklist Externalizing and Total Problem Scale scores, as well as more functional impairment on the Child and Adolescent Functional Assessment Scale compared with MH users without arrests. The fact that many juveniles who commit criminal offenses also have MH needs and that many youth who receive MH services commit criminal offenses indicates the importance of coordinating services under a multisystemic model of therapy, with attention to the types of MH disorders distinctive for youth who commit offenses. 5 tables and 39 references