The authors compared the course of Substance Use Disorders (SUD) in patients with SUD plus schizophrenia (SCZ) with those having SUD only. Data were obtained through diagnostic interviews and questionnaires on consecutive out-patients and in-patients referred for SUD to two university medical centers with alcohol-drug programs. This study revealed the SCZ-SUD patients (n = 29) had demographic characteristics, onset of their substance use, course of use/abuse, and lifetime SUD diagnoses that closely resembled those with SUD-only (n = 296). The marked similarities argue for a course of SUD in schizophrenic patients that is fully as morbid as that in SUD-only patients. The few differences in course appear linked to the following: (1) patients with SCZ using caffeine early, perhaps to relieve prodromal manifestations of schizophrenia, (2) patients with SCZ-SUD later using less or avoiding use of substances that exacerbate symptoms of schizophrenia (e.g., caffeine, cocaine, opiates), and (3) using tobacco more often to ameliorate the symptoms of schizophrenia or the side effects of medications used to treat schizophrenia. Contrary to expectation, those with comorbid SCZ-SUD employed self-help to deal with SUD as often as did the SUD-only patients.