Studies across fields such as science education, health education, health behavior, and curriculum studies identify a persistent gap between the aims of the school curriculum and its impact on students' thinking and acting about the real-life decisions that affect their lives. The present study presents a different story from this predominant pattern in the literature. Through a year-long ethnographic investigation of a health-focused New York City public high school's HIV/AIDS and sex education program, this study illustrates a case in which 20 12th grade students respond positively to their education on these topics and largely assert that school significantly influences their perspectives and actions related to sexual health decision-making. This paper presents the following interpretation of this positive influence: school culture influences these students' perspectives and decisions around sexual health by contributing to the formation of students' identities. This paper further shows how science learning in particular becomes important for students in relation to decision-making when it is linked to issues of identity. These findings suggest that, in addition to attending to the design of classroom curriculum, HIV/AIDS and sex education researchers and curriculum developers (as well as those in science education focusing on other controversial science topics) might also explore the kinds of relational and school-wide factors that potentially influence students' identities, decisions, and responses to school learning.