Summary Greek authorities registered over 3,300 unaccompanied asylum-seeking and migrant children arriving in Greece in the first seven months of 2016. Many of these children had fled violence and armed conflict in their home countries, including Syria, Afghanistan, and Iraq. Others were escaping discrimination and crushing poverty. Alone in Greece without parents or an adult responsible for their care, these children are entitled to care and protection from Greek authorities. However, Greece has a chronic shortage of suitable accommodation and lacks a comprehensive protection system for child asylum seekers and migrants. These factors have led to the prolonged arbitrary detention of children—often in poor and degrading conditions—in protective custody at police stations, in pre-removal detention centers, and in closed facilities on the Greek islands while they await transfer to a dedicated shelter facility. The Greek government justifies the detention of unaccompanied children as a temporary protection measure in the child’s best interest. In practice it is anything but. This report, based on research conducted by Human Rights Watch in mainland Greece from June 27 to July 6, 2016, primarily documents problems with the detention of unaccompanied children in police custody. However, because some of the children interviewed also spent time detained in Coast Guard facilities, or in facilities run by the First Reception Service, the report also addresses aspects of detention conditions at these sites. Human Rights Watch found, first, that unaccompanied children face routine, arbitrary detention. Under international law, binding European directives, and national law, detention of unaccompanied children can be used only as a measure of last resort, in exceptional circumstances, and for the shortest appropriate period. However, children are being detained as a matter of course and for prolonged periods. Greek law allows the detention of unaccompanied children in protective custody while awaiting transfer to a shelter for 25 days, and for up to 45 days under very limited circumstances. Yet children are being detained for longer than these already lengthy periods. Records at one police station showed that the eight children held there had been 1 HUMAN RIGHTS WATCH | SEPTEMBER 2016