While it has been established that many women quit smoking during pregnancy, little is known about postpartum maintenance of smoking cessation and relapse. A sample of 567 women were surveyed at about 6 months postpartum in order to (a) describe the patterns of smoking relapse; (b) assess the perceived importance of smoking cessation in pregnancy and postpartum; and (c) identify potentially high risk situations for smoking relapse. Results indicate that about half (56%) of the women who quit smoking during pregnancy relapse to smoking by 30 days postpartum. Most of these relapses occur in the company of other smokers. Socializing and/or living with a smoker had a powerful negative impact on ability to maintain abstinence in postpartum. Smoking cessation programs for pregnant women should emphasize the importance of continued abstinence in postpartum.