["TESOL Quarterly, EarlyView. ", "\nAbstract\nThis article provides an overview of how learner corpora, defined as collections of texts produced by second or additional language learners, have been used in applied linguistics. It starts by offering a brief history of the methodology of learner corpus analysis, introduces a typology of learner corpora, and outlines a few foundational concepts and analytic approaches in learner corpus research. To illustrate the impact that learner corpora have had on our field, the article then summarizes two recent studies that model best practices in learner corpus research (Gries & Wulff, 2021; Wang, Wang & Wang, 2024) and the insights they have provided into learner language development. The article also offers guidelines for research based on learner corpora that can help us gain a better understanding of second language learning and positively impact language pedagogy. It closes with a discussion of future tasks for learner corpus researchers, focusing on required resources and research activities.\n"]