The new field of computer learner corpus research has roots both in corpus linguistics and second language acquisition (SLA) studies, using the methods and tools of corpus linguistics to gain better insights into authentic learner language. This volume presents articles on all aspects of computer learner corpus research. Although the main focus of the book is English as a Foreign Language, the approach can also be applied to other foreign languages. Part I gives a general outline of learner corpus design and analysis; in Part II, these are put into practice through a series of case studies examining various aspects of learner lexis, discourse and grammar; Part III shows how learner corpus based studies can help improve pedagogical tools (EFL grammars, writing textbooks, electronic tools). Implications for classroom methodology are also highlighted.