Subjects included 267 Serious 602 Offender Project (SOP) clients and 102 control cases followed up for 36 months. A SOP client subgroup (E2) was analyzed separately because of its older age and significantly higher criminality relative to other SOP clients and controls. E2 subjects were arrested for more violent and serious offenses than were other SOP or control subjects, but were rearrested less often. Conversely, other SOP subjects and controls were arrested more frequently but for less serious offenses. However, for self-reported crimes, significant differences were found only for sex, not for treatment. Justice system penetration (seriousness of disposition) following termination of probation supervision was greatest for E2 subjects and least for other SOP subjects. Research instruments and supplemental data are appended. Tables, figures, and 88 references.