The extent to which therapeutic community (TC) methods meet the treatment needs of offenders with substance abuse disorders and co-occurring psychiatric disorders in prison is largely unknown. Very little research has been conducted with this population. The purposes of this study were to generate profiles of co-disordered drug offenders entering TC treatment in prison and to assess their post-release reincarceration rates, compared with drug offenders without psychiatric disorders. Extensive intake interview data for over 8,500 men and women who received treatment in one of 16 prison-based TCs in California were analyzed to produce profiles of co-disordered participants. Intake data come from a 5 year process and outcome evaluation of the California Department of Corrections' (CDC's) treatment initiative. Post-release reincarceration rates come from the CDC's Offender Based Information System. Compared with non-psychiatric disordered drug offenders, co-disordered offenders had substantially more severe substance abuse and criminal histories, in addition to their psychiatric impairment, at treatment entry. Logistic regression results indicated that, compared with drug offenders without psychiatric illness, co-disordered offenders were significantly more likely to be reincarcerated during the first year of their parole. These results suggest that prison treatment programs may need to use more comprehensive diagnostic assessments at intake to assess the diverse mental health needs of drug offenders with co-occurring psychiatric disorders and to develop treatment approaches suitable for this population. Copyright © 2004 John Wiley & Sons, Ltd.