This guideline provides global, evidence-informed recommendations on daily iron supplementation in infants and children, as a public-health intervention for the prevention of anaemia and iron deficiency. It includes recommendations for iron supplementation in countries where malaria is prevalent. The guideline aims to help Member States and their partners in their efforts to make informed decisions on the appropriate nutrition actions to achieve the Sustainable Development Goals, in particular, Goal 2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture. It will also support Member States in their efforts to achieve the global targets set in the Comprehensive implementation plan on maternal, infant and young child nutrition, as endorsed by the Sixty-fifth World Health Assembly in 2012, in resolution WHA65.6, and the Global strategy For women's, children's, and adolescents' health (2016-2030). The recommendations in this guideline are intended for a wide audience, including policy-makers, their expert advisers, and technical and programme staff at organizations involved in the design, implementation and scaling-up of programmes for anaemia prevention and control, and in nutrition actions for public health. This document presents the key recommendations and a summary of the supporting evidence.