We assessed the co-occurrence of DSM-III-R axis I and II disorders and self-reported psychologic distress in inpatients with eating disorders with and without substance use disorders (ED-SUD and ED groups, respectively) and in a matched comparison sample with substance use disorders but no eating disorder (SUD group). The three groups showed similar distributions of axis I disorders but differed in the distribution of axis II disorders. Cluster B personality disorders were diagnosed more frequently in SUD and ED-SUD groups than in the ED group. In contrast, cluster C personality disorders were diagnosed more frequently in the ED group than in SUD and ED-SUD groups. The SUD group reported greater psychologic distress than ED and ED-SUD groups. Possible implications of the observed group differences for psychologic models of why these disorders may be associated are considered.