This guideline provides global, evidence-informed recommendations on preventive chemotherapy (deworming), as a public health intervention in areas endemic for soil-transmitted helminths, to decrease the worm burden of soil-transmitted helminth infections in children, adolescent girls, women of reproductive age and pregnant women, including those coinfected with HIV. The recommendations contained in this guideline are intended for a wide audience, including policy-makers and their expert advisers as well as technical and programme staff at government institutions and organizations involved in the design, implementation and expansion of programmes to control soil-transmitted helminth infections and nutrition-sensitive actions for a safe and hygienic environment to improve public health. This guideline aims to help WHO Member States and their partners to achieve the United Nations Sustainable Development Goals and the global targets presented in the World Health Assembly resolution WHA66.12 on Neglected tropical diseases, the Comprehensive implementation plan on maternal, infant and young child nutrition, the Global strategy for women’s, children’s, and adolescents’ health (2016–2030), Water, sanitation and hygiene for accelerating and sustaining progress on neglected tropical diseases: a global strategy 2015–2020, Accelerating work to overcome the global impact of neglected tropical diseases: a roadmap for implementation, Accelerating progress on HIV, tuberculosis, malaria, hepatitis and neglected tropical diseases: a new agenda for 2016–2030 and Eliminating soil-transmitted helminthiases as a public health problem in children: progress report 2001–2010 and strategic plan 2011–2020.