Gaps in data covering refugees, asylum seekers, migrants and internally displaced populations are endangering the lives and wellbeing of millions of children on the move, warned five UN and partner agencies today. In 'A call to action: Protecting children on the move starts with better data', UNICEF, UNHCR, IOM, Eurostat and OECD together show how crucial data are to understanding the patterns of global migration and developing policies to support vulnerable groups like children.