This book takes stock of current research into computer learner corpora conducted both by ELT and SLA specialists. It should be of particular interest to researchers looking to assess its relevance to SLA theory and ELT practice. Throughout the volume, emphasis is also placed on practical, methodological aspects of computer learner corpus research, in particular the contribution of technology to the research process. The advantages and disadvantages of automated and semi-automated approaches are analyzed, the capabilities of linguistic software tools investigated, the corpora (and compilation processes) described in detail. In this way, an important function of the volume is to give practical insight to researchers who may be considering compiling a corpus of learner data or embarking on learner corpus research. The volume is divided into three main sections: Section 1 gives a general overview of learner corpus research; section 2 illustrates a range of corpus-based approaches to interlanguage analysis; and section 3 demonstrates the direct pedagogical relevance of learner corpus work.