Implementing and evaluating smoking cessation interventions in underserved populations has been found difficult due to high rates of non-adherence to the prescribed protocol. To understand better the barriers to cessation participation, we studied low-income inner-city pregnant women who were enrolled in either a standard or highly intensive quit smoking counseling program. The results showed that 1) in the prenatal phase, non-attendance was predicted by a greater number of cigarettes smoked per day; 2) in the postpartum follow-up phase, non-attendance was predicted by lower educational level and higher self-efficacy for quitting smoking; and 3) participants with more children living at home were at increased risk of rescheduling the postpartum follow-up session. These findings suggest that innovative delivery strategies are needed more effectively to assess and address risk factors for non-adherence to smoking cessation trials among underserved minority pregnant/postpartum smokers.