Research based on Seligman's model indicates that a pessimistic explanatory style predicts increased frequency of depression, poorer physical health, and lower levels of achievement. The data show that persons who have a pessimistic outlook on life are more frequent users of the medical and mental health care delivery systems. This paper describes the development of a bipolar MMPI Optimism-Pessimism (PSM) scale that is based on the results of a technique–Content Analysis of Verbatim Explanation (CAVE)–applied to the MMPI. Reliability and validity indices show that the PSM scale is highly accurate and consistent with Seligman's theory. Identification of the patient's explanatory style may lead to improved management because intervention measures can be directed more accurately according to the patient's personality style. The new scale also will allow researchers to use existing MMPI data to explore relationships between explanatory style and various outcome variables and behavioral correlates.