Studies have revealed a significant adverse impact of comorbid personality disorders on treatment tenure and outcome in a variety of psychiatric and substance abuse populations. We investigated whether this negative relationship also exists among 137 urban, poor, cocaine abusers in behaviorally oriented treatment. Axis II diagnoses were generated categorically using the SCID-II as well as dimensionally using numbers of SCID-II symptoms within diagnostic categories. Contrary to expectations, there were no significant differences between subjects with and without various categorical personality disorders on any outcome measures. Categorical Axis II diagnoses were also minimally correlated with drug use severity, depression, and anxiety at intake, indicating that these were not potential coveriates of outcome. However, dimensional analyses of personality symptoms generated from the SCID-II accounted for substantial proportions of variance in treatment outcomes. Implications of these data for Axis II assessment and drug treatment planning are discussed.