Abstract
While children in general are usually seen as a societal priority, many children are disadvantaged by marginalisation, with adverse effects on health and development. Following feasibility studies the European Commission has now adopted a formal Child Guarantee of service access. This paper links the Feasibility Studies to other reports on the need to address marginalised and institutionalised children. The problems in identifying and quantifying such children are outlined, the challenges of planning for these groups of children, and difficulty of finding universal definitions and data. This European Union initiative is timely, given that around a quarter of European children are marginalised, while the effects of Covid-19 will add to this marginalisation.