The campaign to end the detention of children, including child migrants and asylum seekers, has generated impressive global momentum. However, there remain important gaps in this effort, including the absence of an adequate definition of the immigration detention of children and inherent problems in developing realistic statistics to measure state activities. The objective of this GDP paper is to help encourage discussion of this issue by making some preliminary proposals on a way forward, in particular by proposing the development of a methodology that would allow for careful designation of custodial arrangements focusing narrowly on the facilities used to accommodate child migrants and asylum seekers. Read report.