There were no differences between the groups of offenders (121 sex offenders, 105 other types of offenders, and 21 female offenders) on IQ (intelligence quotient) scores. After 1 year of follow up, the sex offenders reoffended at a rate of 10.5 percent, increasing to 17.9 percent after 3 years, and stabilizing at 15-20 percent for the remainder of the 12-year period. For "other offenders," 17. 2 percent had reoffended after 1 year, 42.4 percent after 3 years, and 40-45 percent until 12 years. Female offenders had lower reoffending rates at all periods of the follow up compared to the other two groups. Unlike previous studies, sex offenses predominated in the reoffending of the sex offender cohort, and other types of offenses were prevalent in the other two cohorts. A significant amount of harm reduction was recorded for those who reoffended. Female offenders had higher rates of mental illness, although mental disorders for the male cohorts were generally high at approximately 32 percent. The cohort of sex offenders had fewer problems with anger and aggression as well as alcohol abuse, but had a higher level of daily living problems and relationship problems. Female offenders had high rates of all problems examined except daily living problems. Regarding services received, all participants had a review of their legal histories, structured psychiatric and psychological assessment, a structured occupational therapy assessment, and a nursing assessment. All participants had reviews of ongoing treatment and case management. 9 tables and 52 references