This report discusses why it is often difficult to find data on missing migrants disaggregated by age. It explores what measures could be taken to improve data on missing migrant children, to help improve policy options and to prevent these tragedies from occurring. The report is a contribution to the joint efforts of UNICEF, UNHCR, IOM, Eurostat and OECD to improve data on migrant and refugee children. Without better data on missing migrants, any policy understanding of children’s migration journeys and the risks and vulnerabilities they face will remain incomplete.