Study objective: To determine the association between childhood abuse and becoming a smoker. Design: Retrospective cohort study. Setting: Boston, Massachusetts. Participants: 722 women aged 36-45 years who completed the baseline questionnaire for the Harvard study of moods and cycles and the survey of interpersonal relationships. Main results: Women who experienced either physical or sexual abuse as a child were 40% more likely to begin smoking compared with women with no history of abuse (95% CI 1.0 to 2.0). Virtually all of this association was confined to sexual abuse (OR = 2.2, 95% CI 1.1 to 4.3) as compared with physical abuse (OR = 0.7, 95% CI 0.7 to 1.6). However, the joint effect of experiencing both physical and sexual abuse as a child led to a 3.5-fold increase in the likelihood of becoming a smoker (95% CI 1.3 to 9.4) compared with women who did not experience any childhood abuse after adjustment for religion, social class, and poverty. Conclusions: Women who experience childhood abuse, even in the absence of depression, are at increased risk of becoming cigarette smokers.