The study objective was to evaluate the relationship between a personality disorder (PD) diagnosis and criminal behavior among drug- and alcohol-dependent patients both retrospectively and prospectively. We examined 1-year pretreatment and 1-year post-treatment crime rates among 370 drug- and/or alcohol-dependent patients. Hierarchical logistic regression was used to examine the predictive value of DSM-III-R PD diagnoses after controlling for demographic features and type and severity of substance dependence. Patients with a diagnosis of antisocial PD (ASPD) were more likely to report having committed a variety of crimes, including violent crimes, during the pretreatment period. Individuals with more PD diagnoses or a diagnosis of borderline PD (BPD) or schizoid PD also reported a greater number of pretreatment violent crimes. In addition, the number of PD diagnoses was correlated with the number of crimes against property. During the pretreatment period, significant interactions were also found between PD measures and substance use in relation to both property crimes and violation of parole or probation. During the posttreatment period, a diagnosis of BPD predicted the commission of violent crimes. In contrast, a cluster A PD predicted a lower frequency of crimes against property. ASPD did not predict criminality during the 1-year follow-up period. In conclusion, a PD diagnosis, particularly ASPD, was associated with a variety of criminal behaviors during the 1-year period preceding substance abuse treatment. Following treatment, PD diagnosis had limited value in the prediction of criminal behavior. Possible explanations for these findings are discussed.