Patients with alcohol and other substance abuse problems have poorer prognoses if there is a concomitant psychiatric diagnosis. However, becauseseverity of psychiatric problemscontributes more than thespecific psychiatric diagnosisto prognosis, the nature of the interaction between substance abuse treatment outcome and an accompanying psychiatric diagnosis can be questioned. In this article an attempt is made to understand the poor-prognosis-with-psychiatric-diagnosis interaction through a literature review and an analysis of various problem areas that clients bring to substance abuse treatment. Problem areas were measured with a variety of instruments. The results show that groups that vary in severity of psychiatric problems also differ in severity of problems in other areas. As there is no doubt that such dual diagnosis patients pose a considerable treatment challenge, the implications of these findings for theoretical consideration and treatment planning are discussed.