This report presents the findings of the 2018 School Water, Sanitation and Hygiene (SWASH) Assessment survey. This survey was implemented through a multi-sectoral collaboration of the National Bureau of Statistics (NBS) and the Office of the Chief Government Statistician (OCGS) Zanzibar; the Ministry of Education, Science and Technology (MoEST); the Ministry of Education and Vocational Training, Zanzibar (MoEVT); President’s Office Regional Administration and Local Government (PO–RALG); and President’s Office Regional Administration, Local Government and Special Departments (PO–RALGSD), Zanzibar. The 2018 School Water, Sanitation and Hygiene (SWASH) Assessment is the first comprehensive, nationally representative survey of primary and secondary schools designed to provide information about the status of safe drinking water, adequate sanitation and hygiene facilities as well as appropriate hygiene practices in Tanzania.