This study corroborates the findings of other similar studies in showing that even in the current sample of mostly first-time offenders, psychosocial behaviors, once established, had a strong likelihood of continuing over time. At each time point, significant interrelationships were found among the youths' psychosocial problems, drug problems, and self-reported delinquency. These data were limited, however, by the fact that they reflected only two points in time, so the finding regarding the continuity of psychosocial problems over time should be interpreted with caution. Future studies should examine the continuity of psychosocial problems over longer time periods with larger datasets. They should also include both delinquents and nondelinquents. Although the intervention strategy used with the current sample was unsuccessful in changing psychosocial problems and related problem behaviors, early intervention holds promise of reducing the probability that troubled youth will continue criminal and high health-risk behaviors into adulthood. Between June 2002 and May 2004, arrested youth placed in a juvenile justice diversion program in Hillsborough County, FL participated in an experimental, prospective clinical trial that evaluated an innovative intervention service. It consisted of 16 weeks of case-management services. Baseline intake interviews were completed for the 165 youth and their parents/guardians. One year later, followup interviews were completed with 137 of the youth. The Comprehensive Adolescent Severity Inventory was used to assess youths' psychosocial functioning in the areas of family, peer associations, and school performance. Drug use and delinquency were determined from self-reports. 2 tables, 2 figures, and 61 references