In the New Jersey study, 33 percent of the sample (n=718) committed a new offense after their release, 14 percent committed a new sex offense, and 24 percent committed a new nonsexual offense. Compared to the men who did not receive treatment in prison (n=223), those who received sex-offender-specific treatment in prison (n=495) had a lower recidivism rate only for nonsexual offending. Apparently, the treatment did not have the effect of preventing repeat sex offenses. Sexual offenders younger than 40 years old who had at least one prior arrest for a sexual offense and two prior arrests for a nonsexual offense were nine times more likely to repeat a sex offense compared to sexual offenders older than 40 who did not have prior arrests for sex offenses. Age and prior offense had an even stronger effect on nonsexual reoffending. The treatment sample was treated at New Jersey's Adult Diagnostic Treatment Center (ADTC), which is the only facility in the State that provides for the specific treatment and incapacitation of sexual offenders. The treatment provided is consistent with other North American treatment programs; both cognitive-behavioral treatment and relapse prevention are provided. Those who received no treatment were incarcerated in the general population. The total sample included all sexual offenders released from the ADTC and the general population during the period 1994 through 1997. Both treatment and nontreatment samples were followed to determine recidivism until January 2001, providing followup time frames that ranged from approximately 7 years for those released in 1994 and 4 years for the 1997 cohort. Rearrest, reconviction, and reincarceration rates were used in combination in order to increase the validity of the study. 4 tables, 1 figure, and 39 references