Co-occurrence of psychopathy (assessed with the Psychopathy Checklist) and lifetime Diagnostic and Statistical Manual of Mental Disorders (3rd ed.) alcohol and drug disorders (assessed with the National Institute of Mental Health Diagnostic Interview Schedule) was examined in a sample of 360 male inmates. Consistent with previous research that used diagnoses of antisocial personality disorder, psychopaths were more likely than nonpsychopaths to have lifetime diagnoses of alcoholism, any drug disorder, and multiple drug disorders. We also examined the relation between substance abuse and the 2 factors of the Psychopathy Checklist. Substance abuse was significantly related to general social deviance (Factor 2) but was unrelated to core personality features of psychopathy (Factor 1). We present two possible models of psychopathy (unitary syndrome vs. dual-diathesis model) that may account for the association between psychopathy and substance abuse.