Research on how religion shapes contraceptive practices and fertility has paid insufficient attention to how people interpret religious teachings. This study draws on ethnographic fieldwork in Degollado, Mexico, to describe generational and social-contextual differences in how women interpret and use religious doctrine to achieve their fertility desires without jeopardizing their standing as devout Catholics. Contrasting the family planning beliefs and practices of young Mexican women with those of older women (many of whom are the younger women's parents and in-laws), in a rural town in which the religious regulation of everyday life is pervasive, reveals how a common set of religious teachings and principles can be used to guide two different generational strategies for fertility regulation. The ethnographic data presented here highlight the creativity with which people use religious frameworks to justify their behavior. Research exploring how religion—and culture more broadly—influences fertility and contraceptive use should give greater attention to the dynamic interplay between cultural beliefs and institutions, social context, and interpretive agency.