An estimated 500,000-plus people are on parole each year, many with serious co-occurring psychiatric and substance use disorders. Using cross sectional, self-report data this study examined the relationships between parolee time to rearrest, serious mental illnesses, and substance dependency (n = 1,121). Regression analyses indicated that after controlling for demographic and criminal justice variables, parolees with serious psychiatric and substance dependence disorders were rearrested faster than nondually diagnosed parolees (p less than 0.05). An explanation is that compared with parolees without dual diagnoses, parole violations by dually diagnosed parolees are detected and punished more quickly because of closer parole supervision. (Contains 3 tables.)