Despite national guidelines advocating a comprehensive, age-appropriate, and sequential approach to sexual health education in schools, many young people in the USA do not receive sexual health information until high school. To date, there has been little research on the need for a supplemental round of sexual health education -- a 'booster' -- later in adolescence to reinforce and expand upon information and skills previously provided. In rural California, we conducted six focus groups with young people (N = 22, ages 14-20) and key informant interviews with youth-serving professionals (N = 10) to examine the sexual health education needs of youth as they complete high school. Five themes were identified, indicating a need for booster education that 1) reinforces existing sexual health knowledge; 2) expands beyond traditional areas of sexual health education; 3) addresses community stigma about adolescent health; and 4) prepares young people for the transition to adulthood. In addition, booster education should 5) be established within the school system to promote an environment that addresses and normalises health issues throughout the school year. Providing booster sexual health education may meet critical gaps in efforts to support the healthy sexual development of young people, especially those living in rural communities.