Abstract: Improper confinement of children in migration contexts – unnecessary, prolonged, or in harmful conditions – is a severe and troubling phenomenon. In that regard, the UN Human Rights Committee’s General Comment No. 35 (2014) summarizes the treaty body’s interpretation of the right to liberty of person, including protection against arbitrary detention, under the International Covenant on Civil and Political Rights, one of the principal human rights treaties at the global level. This essay describes the Human Rights Committee’s approach to detention of migrants, including child migrants. It explains why General Comment No. 35 employs a broad definition of “detention,” and the resulting need for a nuanced and non-absolutist approach to the “detention” of children in migration contexts. Such “detention” is not invariably arbitrary, but rather should be used only as a measure of last resort, and for the shortest appropriate period of time.