ABSTRACT
Learner language is "the oral or written language produced by learners" and it is one of the major topics in the field of second language acquisition (SLA). Research in this area revolves around the key notion of interlanguage. Selinker was one of the first authors to suggest that learner language emerges during the course of learning and needs to be seen as a system with its own structure. This chapter discusses the importance of learner corpora as a powerful tool for studying learner vocabulary. It describes features of such corpora and types of methodologies that can be applied to analyze learner data. The chapter presents a number of ways in which learner corpora can facilitate research into L2 lexical learning as well as tracking L2 learners' lexical development over time. Finally, it explains how learner corpora can be usefully applied to assess learner language and develop teaching materials.
