The global effort to achieve sanitation and water for all by 2030 is extending beyond the household to include institutional settings, such as schools, healthcare facilities and workplaces. This has been reinforced by global education for all strategies highlighting how water, sanitation and hygiene (WASH) in schools improves access to education and learning outcomes, particularly for girls, by providing a safe, inclusive and equitable learning environment for all. This report is the first comprehensive global assessment of WASH in schools and establishes a baseline for the Sustainable Development Goal (SDG) period.