OBJECTIVE: To examine a measure of explanatory style, the Optimism-Pessimism (PSM) scale derived from college-entry Minnesota Multiphasic Personality Inventory scores, as a predictor of all-cause mortality. SUBJECTS AND METHODS: A total of 7007 students entering the University of North Carolina at Chapel Hill completed the Minnesota Multiphasic Personality Inventory during the mid-1960s. Of those students, 6958 had scores on the PSM scale and data for all-cause mortality through 2006. Scores on the PSM scale were evaluated as predictors of mortality using the Cox proportional hazards regression model, adjusted for sex. During the 40-year follow-up period, 476 deaths occurred. RESULTS: Pessimistic individuals who scored in the upper tertile of the distribution had decreased rates of longevity (hazard ratio, 1.42; 95% confidence Interval, 1.13-1.77) compared with optimistic individuals who scored in the bottom tertile of the distribution. CONCLUSION: In a model that adjusted only for sex, a measure of optimistic vs pessimistic explanatory style was a significant predictor of survival during a 40-year follow-up period such that optimists had Increased longevity.