Children and families around the world are fleeing violence in their home countries, and many nations are responding through detrimental practices that include family separation and the detention of migrants and asylum-seekers - including children - although the UN Committee on the Rights of the Child recommends that countries “expeditiously and completely cease the detention of children on the basis of their immigration status.” This article describes the extreme psychological distress experienced by unaccompanied migrant children and the heightened adverse effects for those being detained and the reasons States are using immigrant detention despite its negative consequences.