Abstract Background: Barrett's esophagus (BE) is a precursor lesion of esophageal adenocarcinoma. Besides gastroesophageal reflux, possible risk factors for BE include overweight, cigarette smoking, and alcohol consumption. Our objective was to study these associations by using prospective data. Methods: The prospective Netherlands Cohort Study, initiated in 1986, consists of 120,852 men and women, aged 55 to 69 years at baseline. At baseline, all subjects completed a questionnaire on dietary habits and lifestyle. After 16.3 years of follow-up, 370 BE cases with specialized intestinal metaplasia and 3,866 subcohort members were available for case–cohort analysis. Cox proportional hazards models were used to calculate incidence rate ratios (RR) and 95% CIs. Results: Body mass index (BMI) at baseline was associated with risk of BE in women [multivariable adjusted RR per 1 kg/m2, 1.07 (1.03–1.11)] but not in men [RR per 1 kg/m2, 0.99 (0.93–1.05)]. The association in women was not specifically due to abdominal overweight. Former cigarette smokers were at increased risk of BE (RR = 1.33, 95% CI: 1.00–1.77), but current smokers were not. Smoking duration showed a positive association with BE risk (Ptrend = 0.03). For alcohol consumption, the RR per 10 g ethanol/d was 0.95 (0.87–1.03). Conclusions: Increased BMI was a risk factor for BE in women but not in men. Several aspects of cigarette smoking were positively associated with BE risk. Alcohol consumption was not associated with an increased risk of BE. Impact: Future research should focus on risk factors both for development and for progression of BE to esophageal adenocarcinoma. Cancer Epidemiol Biomarkers Prev; 20(2); 345–58. ©2010 AACR.