Migrant and asylum-seeking children are particularly vulnerable and therefore need special protection against the multiple dangers they face along their journey: violence, sexual abuse, human trafficking and exploitation. Many forms of violence against migrant and refugee children lead to their disappearance or await those whose trace is lost, as they “vanish” into clandestine networks which remove them ever further from the protection and care to which they are entitled, first and foremost as children, then as migrants and refugees. This report describes the situation concerning missing refugee and migrant children, underlining the difficulty in knowing its actual dimensions. It examines the applicable legal provisions and recommends better protocols to protect children and prevent disappearances. Member States should ensure that undocumented child migrants are registered and identified with public authorities and that an individual guardian is appointed to an unaccompanied child refugee or migrant. Refugee and migrant children have the right to family reunification. Thus, they should be accommodated as far as possible with their families in accordance with each child’s right to live with their parents as enshrined in Article 22 of the United Nations Convention on the Rights of the Child.