In this article, I aim to trace the increasing use of detention as a central plank of asylum policy, its effect on children in asylum seeking families and consider whether the introduction of the ‘welfare principle’ in section 55 of the Borders, Citizenship and Immigration Act 2009 and the statutory guidance attached to it, will have a positive impact on the children of asylum seeking families. In particular, I would like to challenge the assumption that lies at the heart of many of the arguments put forward in this area, that the detention of children is necessary in the interests of immigration control.