In 2015, the world’s countries agreed on the Sustainable Development Goals (SDGs), yet nearly 5 years later, few countries have recorded much progress towards achieving them. This Commission presents the case for placing children, aged 0–18 years, at the centre of the SDGs: at the heart of the concept of sustainability and our shared human endeavour. The report includes a new global index of 180 countries, comparing performance on child flourishing, including measures of child survival and well-being, such as health, education, and nutrition; sustainability, with a proxy for greenhouse gas emissions, and equity, or income gaps.