The authors evaluated an expanded measure of intrinsic and extrinsic motivation for smoking cessation in a population-based sample of 897 pregnant smokers (500 current smokers and 397 recent quitters). The measure assessed motivation related to pregnancy and parenthood in addition to general intrinsic and extrinsic dimensions. Current smokers at baseline who quit smoking by 28 weeks of pregnancy (n = 102) had significantly higher baseline levels of pregnancy-related motivation than continuing smokers. Extrinsic and pregnancy motivation dropped between baseline and 28 weeks of pregnancy among continuing smokers. Higher levels of intrinsic relative to extrinsic motivation at baseline were associated with sustained abstinence during the first 2 months postpartum. Results suggest that both general and pregnancy-specific motivation are important for smoking cessation and relapse prevention during pregnancy. Interventions to enhance the salience of health benefits over and above those related to pregnancy and other intrinsic benefits of a greater sense of self-control could protect against postpartum relapse.