Though many women spontaneously quit smoking during pregnancy, a large proportion relapse after delivery. Efforts aimed at reducing postpartum smoking relapse have been largely ineffective. Several studies have reported breast feeding as a primary factor influencing smoking abstinence duration. However, data on the potential role of breast feeding in smoking intervention efforts remain incomplete. The Ulm SPATZ Health Study cohort consists of 1006 newborns of 970 mothers recruited in the University Medical Center Ulm, Germany. Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models were used to assess differences in predominant and total breast-feeding duration stratified by smoking abstinence at 2 years and relapse period (by 6 weeks, 6 months, and 2 years postdelivery). Chi-square and Kruskal-Wallis tests were performed to identify significant differences in demographic and lifestyle factors across smoking categories. Approximately 70% of previous smokers who initiated breast feeding relapsed within 2 years. Relapse by 6 months was significantly associated with noninitiation of predominant breast feeding. Total breast-feeding duration rates among abstaining mothers and those who relapsed after 6 weeks mirrored those of nonsmokers respectively up to 1 year and 3 months. Lower age and education were mostly associated with smoking by 6 weeks. First parity and having a nonsmoking partner were associated with abstinence up to 2 years. Interventions promoting breast feeding to incentivize continued smoking abstinence may be effective prior to weaning. Those promoting breast feeding longer than 6 months and partner smoking cessation may increase rates of long-term smoking abstinence lasting longer than 2 years postdelivery. Most mothers who quit smoking during pregnancy relapse within 6 months of delivery. Though interventions targeting new mothers have been largely unsuccessful, relapse is often delayed until after weaning and targeted breast-feeding promotion has been suggested to enhance smoking cessation interventions. In this study, we assess the relationship between breast-feeding duration and long-term smoking abstinence by longitudinally investigating predominant and total breast-feeding patterns among mothers with a recent history of smoking stratified by period of relapse up to 2 years after delivery.