The Sexuality Education Review and Assessment Tool (SERAT) is an Excel-based tool that helps to collect data on school-based sexuality education programmes, to generate reflection and discussion about strengths and areas of improvement of programmes. Its purpose is to: review school-based comprehensive sexuality education programmes based on international evidence and good practice; assess programme strengths and gaps, and inform improvement or reform; assess programme relevance in relation to health, education, gender and legal & policy context data; stimulate debate and strengthen advocacy efforts through producing data on comprehensive sexuality education that is accessible to different audiences. This current version of SERAT (3.0) was completed in 2020, based on the original version of SERAT developed in 2012, and the Revised UN International Technical Guidance on Sexuality Education, published in 2018.