The relationship between mental health status and longevity was examined in an archival prospective cohort study (N = 1,103) derived from work begun by Lewis Terman in the 1920s. Degree of psychological maladjustment, cumulatively rated by Terman and his colleagues as of 1950, was found to be related to higher risk of all-cause mortality over a 4-decade follow-up period. The differences among causes of death were nonsignificant, but there was some indication that mental health problems were more strongly related to deaths from injury and cardiovascular disease. The overall relationship was significant for men but weaker for women. The effect was not substantially mediated by alcohol consumption, obesity, or cigarette smoking.