As a burgeoning field of research, much has been written about second language acquisition (SLA), although within this area, foreign language (FL) learning has received less attention than second language (L2) learning. The distinction between FL and L2 learning is that the former is where the target language – the language to be learnt – is not generally spoken in the community, but in the latter case it is. FL teaching and learning is the focus of the current volume, which goes some way to redressing the imbalance of research effort.

In addition to the privileging of L2 over FL learning, the majority of SLA research has focused on adults with much less attention given to younger learners. As such, we often read comments by authors stating that there is a dearth of research about children. This is not to say that young learners have been completely overlooked. In fact, some of the earliest SLA work, beginning in the 1970s, focused on children and there has been a continuing line of work since that time examining SLA for this cohort. Indeed, García Mayo points out in her introduction to this volume that, in recent years, interest in this age group has been increasing. The fact remains, however, that children in primary schools learning FLs is an under-researched area.

One of the unfortunate consequences of this is that the findings from adult SLA research are generalised and used to inform pedagogy for younger learners. Yet, these different-aged learners vary in terms of linguistic, cognitive and social development (Lázaro Ibarrola & Hidalgo, Chapter 5) and, therefore, the process of adult and child SLA is quite distinct. For example, Tellier and Roehr-Brackin (Chapter 2) describe how adults make use of explicit knowledge, whereas children rely on implicit learning which requires prolonged exposure to input. Further, while we understand the contribution of language and metalinguistic language awareness for adult learners, as Muñoz (Chapter 3) points out, less is known about how this manifests for younger learners.