This article examines the willingness of pregnant women to participate in research on health. The authors investigate attitudes toward multiple methods of data collection, including survey and biomarker data collection. Complete interviews were obtained from a sample of 90 pregnant women in a matched control–comparison study of patients receiving prenatal care in private practice and clinic settings. Women experiencing prenatal care at a clinic reported less willingness to participate in research than women experiencing prenatal care at a private practice. Women who deemed “contributing to science,” “learning about pregnancy health,” and “helping future patients” as important motivations for participating in research were more likely to express willingness to participate in a study. African American women reported less willingness to answer questions in a survey than white women. The results suggest that motivational factors should be integrated into the design of a study of pregnant women to encourage participation.