Sexual health education is a well-known, evidence-based intervention that can improve adolescent health outcomes, increase protective health behaviours, and decrease risky health behaviours. Providing sexual health education in school settings offers opportunities for discussion of critical health topics and can improve the school environment for all students. However, not all sexual health education is taught equitably across classroom environments. As part of a mixed-methods study to describe school-based sexual health education, we conducted focus groups and interviews with recently graduated high school students in New Mexico, a geographically and ethnically diverse state in the US Southwest. Thirty-one young people shared their experiences, explored the sexual health education content they had been taught, and offered recommendations to improve sexual health education. Three key themes were developed: young people wanted and needed sexual health education taught in school settings; the sexual health education currently taught in school is not helpful and sometimes harmful; and the individuals who teach sexual health education are critically important. These findings can inform and support school staff and administrators addressing barriers to school-based sexual health education delivery, particularly in schools within marginalised communities with limited resources. The results support including youth as stakeholders in the planning, delivery and evaluation of school-based sexual health education; and the development of sexual health education training for teachers, with the goal of improving health outcomes for all youth populations.