Comprehensive sexuality education is an essential part of a good quality education that helps prepare young people for a fulfilling life in a changing world. It improves sexual and reproductive health outcomes, promotes safe and gender equitable learning environments, and improves education access and achievement. This paper, produced jointly with the Section for Health and Education at UNESCO, discusses how governments can overcome social resistance and operational constraints to scale up these programmes as part of their commitment to SDG 4, the global education goal.