Yet to understand the causes and consequences of monetary child poverty and to design effective anti-poverty policies, it matters if the same group of children remain poor or if every child experiences one brief poverty spell. Adverse consequences of experiencing poverty are well documented and the length of time spent in poverty amplifies its negative impact on key child outcomes (see Brooks-Gunn and Duncan 1997), including cognitive and behavioural development. A recent comprehensive review of income mobility in the European Union by Van Kerm and Pi Alperin (2013) does not focus on children.