This study involved cluster analysis of Millon Clinical Multiaxial Inventory-II (MCMI-II) records of 304 cocaine dependent males and examined differences among personality-based clusters in medical, legal, employment, drug, alcohol, family, and psychiatric problem severity at treatment intake and in outcome status during the 12 months after completion of residential drug treatment. A hierarchical cluster analysis (Ward's method) was used to identify 4 cluster subgroups: antisocial, subclinical, neurotic, and high psychopathology. MANOVA revealed that membership in Neurotic and High Psychopathology Cluster subgroups was linked with more severe family and psychiatric problems at treatment intake than found in the Subclinical Cluster Subgroup (all ps < .05). The High Psychopathology Cluster Subgroup also had more severe drug problems at intake than did the Subclinical Subgroup (p < .05). Logistic regression analysis revealed that membership in the High Psychopathology Subgroup predicted relapse/loss to follow-up status after controlling for age, education, ethnicity, treatment program attended, and pretreatment cocaine use frequency (X(2) = 21.25, df = 3, p < .001).