This study evaluated the prevalence of Axis II disorders in substance abuse patients and the relationship between Axis II psychopathology and two other known predictors of adverse addiction treatment outcomes, i.e., Axis I psychiatric comorbidity and illegal drug use, specifically cocaine. 232 patients with cocaine and/or alcohol dependence were admitted to either inpatient or outpatient addiction recovery programs at Carrier Foundation, a nonprofit, private-pay hospital in New Jersey. Axis II disorders were more prevalent in cocaine than alcohol dependence and in patients with Axis I psychiatric comorbidity. When all three predictors were evaluated in one prediction model, the combination of Axis I and II psychopathology was the best predictor of a return to substance use at one year post-treatment, compared to the three factors alone. These findings highlighted the importance of the interrelationship of the relative prognostic value of three known predictors of addiction treatment.