MMPI data collected from a sample of college men and women during 1964-1967 were used to predict smoking initiation and cessation over a 20-year follow-up period. People who subsequently began smoking were more rebellious, impulsive, sensation seeking, and hostile; were less likely to present a positive self-image; and were socially extraverted while in college. People who continued to smoke 20 years later were more hostile and sensation seeking. The personality variables that predicted smoking initiation and cessation were the same for men and women. Discussion centers on the potential role of hostility as a predictor of smoking cessation.