Learner corpus research lies at the crossroads between four major disciplines: corpus linguistics, linguistic theory, second language acquisition and foreign language teaching. The first part of the article highlights the contribution of these four disciplines and shows that each of them is necessary for an optimal exploitation of the data. Some of the controversies that learner corpus research is currently giving rise to are tackled, in particular the reference to native speaker norms. The second part is devoted to pedagogical applications of learner corpus research. First, the contribution of two types of corpora – corpora for delayed pedagogical use and corpora for immediate pedagogical use – is compared. Secondly, current learner-corpus-informed pedagogical tools are assessed on the basis of the targeted type of proficiency: accuracy, complexity and fluency (Skehan 1998). The article closes with an agenda of priorities for future research.