In Nigeria, research has documented a significant disparity between people's knowledge of HIV/AIDS and the extent to which they act to protect themselves. Data from a survey of 863 adolescent and unmarried young adults, in-depth interviews, and participant observation are combined in this study to explain some of this discrepancy. Young migrants appear to make sexual and contraceptive decisions in relation to gender norms and attitudes concerning procreation at least as much as in relation to fear of disease. Assessments of current and potential partners, choices about whether or not to have sex, and decisions about whether or not to use condoms are influenced by shared cultural values regarding the importance of parenthood. These cultural conceptions of parenthood are gender-specific and put men and women in different negotiating positions with regard to sex and contraception.