Second Language Acquisition is one of the primary areas of research at the CECL. The importance of different variables (age, native language, knowledge of other foreign languages, task, time available, etc.) for language learning has played a major role since the first learner corpora were collected at the CECL. Rigorous data compilation procedures are required to draw valid conclusions from the data and various variables were selected and encoded in the databases. These variables allow for both a more accurate selection of corpora and more precision in the interpretation of results.
All the learner corpora that were collected by the CECL have become references in the field of second language acquisition and have been used by many researchers worldwide to investigate the development and acquisition of vocabulary, grammar, syntax, phraseology and several aspects of the discourse of L2 learners. Research carried out at the CECL has also made it possible to develop new theoretical perspectives on transfer, on the complementarity between corpus and experimental data, and on possible links between corpus and cognitive linguistics. The corpora collected at the CECL are also at the basis of many pedagogical applications.