Sexual and reproductive health and rights (SRHR) are based on the right and the ability of all individuals to decide over their own bodies and to live healthy lives. Comprehensive sexuality education (CSE) is a central component of SRHR, especially for young people. CSE - or the many other ways this may be referred to - is a curriculum-based process of teaching and learning about the cognitive, emotional, physical and social aspects of sexuality. It can be delivered in or out of school. CSE can be transformative when part of a multi-component programme that also provides youth-friendly SRHR services and a dresses related harmful social norms. This brief gives an overview of what CSE is, its importance and how Sida works on it. The intended audience is Sida and Embassy staff, but partners and other stak holders may also find it useful.