This Report Card offers an assessment of child well-being in the context of sustainable development across 41 countries of the European Union (EU) and the Organisation for Economic Co-operation and Development(OECD). This group includes both high- and middle-income economies, but here we refer to them all as high-income countries’ – or ‘rich countries’, for convenience. The concept of child well-being is rooted in the Convention on the Rights of the Child (CRC) but the Agenda for Sustainable Development adds new dimensions. Progress across all these dimensions will be vital to children, and advanced economies will therefore need to monitor the situation of children and young people both nationally and globally.