Research has consistently shown that alcohol consumption motivated by a desire to alleviate negative emotional states predicts alcohol use and relapse among clients with cooccurring psychiatric disorders. However, studies examining the role of drinking motives in people with severe mental illness are few. This study of 283 community mental health clients (43.8% men, 55.1% women), assigned a primary Axis I diagnosis of schizophrenia (28.3%), schizoaffective (23.3%), major depression (31.1%), or bipolar I disorder (17.3%), tested the hypothesis that clients with a diagnosis of mood disorder would report greater substance use, would indicate more problems associated with substance use, and would be more likely to use substances to cope with negative emotions than would clients with schizophrenia. In addition, coping motives would account for more variance in substance use and related problems than would convivial drinking when controlling for age, gender, and Axis I diagnosis. Results largely supported these hypotheses with some exceptions. Implications for theory, research, and practice with comorbid clients are suggested.