Learning English grammar at university: A corpus-based error analysis of Italian B1+ EFL learners

The acquisition of grammatical competence remains a central concern in EFL contexts, particularly in academic settings where written accuracy constitutes an important marker of language proficiency. Error Analysis provides a valuable theoretical and methodological framework for investigating learner language, as it enables researchers to identify systematic patterns of deviation and explore the cognitive and linguistic processes underlying second-language development. This study examines grammatical errors in the written production of Italian learners of English enrolled in the first year of an undergraduate English-language programme at the University of Naples Federico II (CEFR B1/B1+ level). The analysis is based on a corpus of 244 tests collected during the June–July 2024 testing sessions. Adopting a mixed-methods approach, the study combines quantitative and qualitative analyses to identify recurrent error patterns and investigate their underlying causes. Errors are classified according to their linguistic category and interpreted within the framework of interlanguage theory, with particular attention to the distinction between interlingual and intralingual sources. The findings reveal that reported speech, verb tense and aspect, and question formation turn out to be the most problematic grammatical areas for B1 learners.