Archival data from the University of North Carolina Alumni Heart Study were used to assess whether positive, neutral, and negative social comparisons assessed during college predicted the expression of personality during adulthood. College students in 1966 rated themselves relative to peers on several personal attributes. For men and women, these attributes produced 3 similar yet distinct variables reflecting gregariousness, achievement striving, and expressiveness. These students were contacted 20 years later and completed the NEO Personality Inventory and M. Rosenberg's (1965) self-esteem measure. In general, persons with comparatively positive self-evaluations during college viewed themselves as possessing more positive and less negative personality traits during adulthood and were also less likely to report poorer self-esteem during middle adulthood. The implications of social comparison processes for personality development are discussed.