Sexual health is a controversial science topic that has received little attention in the field of science education, despite its direct relevance to students' lives and communities. Moreover, research from other fields indicates that a great deal remains to be learned about how to make school learning about sexual health influence the real-life choices of students. In order to provide a more nuanced understanding of young people's decision-making, this study examines students' talk about sexual health decision-making through the lens of identities. Qualitative, ethnographic research methods with twenty 12th grade students attending a New York City public school are used to illustrate how students take on multiple identities in relation to sexual health decision-making. Further, the study illustrates how these identities are formed by various aspects of students' lives, such as school, family, relationships, and religion, and by societal discourses on topics such as gender, individual responsibility, and morality. The study argues that looking at sexual health decision-making--and at decision-making about other controversial science topics--as tied to students' identities provides a useful way for teachers and researchers to grasp the complexity of these decisions, as a step toward creating curriculum that influences them. (Contains 1 figure and 1 note.)