The number of pupils for whom English is an additional language (EAL) has grown steadily over the past twenty years, increasing by around 300 per cent in England since 1997 (Department for Education, 2018a; NALDIC, 2018a). This linear progression, however, masks wide disparities between groups of pupils and their experiences of education. The large majority are second- or third-generation British citizens born into multilingual homes (Strand and Demie, 2006; Strand, Malmberg and Hall, 2015). English is often their strongest language, so while officially classed as ‘EAL’, it may be more helpful to describe them as ‘multiliterate’ (New London Group, 1996; Datta, 2007) or ‘advanced bilingual learners’ (Conteh, 2012, pp. 12–14), as their different languages play distinct roles in their lives. Others will be new to the United Kingdom, perhaps also new to English and even to formal schooling, but with a set of contextually specific ‘negotiation strategies and a repertoire of codes’ (García, 2007, p. xiii) developed in different settings over time. These learners may have migrated with the intention of settling in the United Kingdom; they may be ‘sojourners’ whose parents are working or studying here for a period of time; or they may ‘transmigrate’, meaning that this is part of a longer migration or that they are regularly resident in a number of countries. Many ‘EAL pupils’ are therefore highly mobile, and such mobile learners are the focus of this chapter.