Teaching about relationships and sex in UK schools often focuses on the biology of reproduction. Stakeholders have called for lessons to cover a broader range of issues, such as healthy relationships and the risks posed by using digital technology. The subject Relationships and Sex Education (RSE) will become statutory in all secondary schools in England in the near future. There is ongoing consultation into what will be included in the statutory guidance for RSE. This POSTnote reviews evidence on the potential outcomes of RSE in schools and how to maximise its effectiveness.