Cigarette smoking has established effects on body weight. The effects of weight concerns on smoking initiation, maintenance, cessation, and relapse, however, are less clear. This review shows that weight concerns are related to smoking behavior in complex ways that differ depending on the smoking outcome (initiation, cessation, relapse), gender, and age. Dieting behaviors and general weight concerns appear to be positively related both cross-sectionally and prospectively to smoking in White adolescent females. In adults, weight concerns specific to smoking cessation appear to be higher in current smokers and may have a negative influence on cessation and relapse. General weight concerns, however, do not differ by smoking status, nor do they appear to hinder cessation or promote relapse. Dieting behavior is most prevalent in former smokers, least prevalent in current smokers, and intermediate in never smokers, suggesting that ex-smokers may be dieting to control cessation-related weight gain. Smoking cessation interventions that promote dieting to control weight have not been successful in preventing cessation-related weight gain, nor have they increased smoking cessation rates. Population-based prospective studies are needed to determine the broader significance of weight concerns in relationship to smoking cessation in adults. Efforts to address weight concerns in smoking intervention programs may need to target a small subset of individuals for whom weight control smoking is a significant barrier to cessation.