This paper introduces the Swedish Learner English Corpus (slec), which consists of argumentative texts in English that are written by Swedish junior and senior high school students. slec includes rich metadata, enabling empirical studies of various extra-linguistic variables. Most noteworthy is the inclusion of detailed information on students’ extramural English activities (ee), such as reading, watching, conversing, gaming and engaging in social media in English. In addition, a sub-set of texts from slec have been assessed for proficiency using the Common European Framework of Reference for Languages (cefr). This paper provides an overview of the corpus compilation process, the metadata, and the available versions of slec. Researchers, teachers and students can access this resource to investigate various aspects of second language use and development, such as the impact of extramural language activities on linguistic complexity.