This report discusses the outcomes of a study that examined Massachusetts' automated court records (CORI) of all arrests by the age of 25 in 82 individuals who had received Boston-area intensive public adolescent mental health services between 1988 and 1994. Clinical records from individuals targeted adolescent treatments were also examined. Results indicated that by age 25, 56.1 percent of adolescents and young adults had been arrested. Six percent had only juvenile records, 27 percent had only adult records, and 23 percent had both, with differences between males and females. A larger portion of males than females had both juvenile and adult records. The earliest age of arrest was 9 years. The hazard rates for first arrest revealed the maximum at age 17 for girls and age 18 for boys. In boys, rates increased from ages 13 to 17, then declined after age 18 to a rate of 0 at age 22. In girls, first arrest risk was low until age 17, declined to 0 at age 20, rose again at age 22, and declined to 0 at age 24. Risk factors for juvenile and adult arrest included gender, length of stay in residential or day treatment, admission age, and adjudicated delinquency. (CR)