This qualitative study explores smoking cessation during pregnancy and the factors that contribute to remaining smoke-free and relapsing. Ninety-four women attending prenatal clinics in central North Carolina who had quit smoking before 30 weeks gestation were enrolled in an observational study that included a face-to-face interview at 4 months postpartum. Results were analyzed for common themes in the two groups: those who remained smoke-free and those who had relapsed. Fetal health motivated pregnant women to quit smoking, while stress, socializing with smokers, cravings, and easy access to cigarettes tempted women to smoke. Women who remained smoke-free postpartum overcame temptations by continuing to acknowledge the health benefits of not smoking and having a strong internal belief system, significant social support, negative experiences with renewed exposure to cigarettes, and concrete strategies for dealing with temptations. For women who relapsed postpartum, factors having the greatest influence on relapse included easy access to cigarettes, lack of social and financial support, insufficient resources for coping with the challenges of childrearing, physical addiction, reliance on cigarettes as a primary form of stress management, and feelings of regret, shame, or low self-esteem. Recommendations for relapse prevention include assessing women who quit during pregnancy for low or high risk of relapse and offering comprehensive interventions and case management for those at higher risk to address the physical, mental, behavioral, and social contexts leading to relapse.