ABSTRACT Learners’ extramural exposure (EE) to English beyond the classroom is becoming increasingly relevant as a site for language learning. EE has risen as a crucial variable in language development, learning and acquisition; however, the interaction between different types of EE and learners’ age remains insufficiently studied. This study explores the interface between biological age (operationalised as school years) and EE in English as a foreign language (EFL) writing performance in secondary school. A cross‐sectional sample ( N = 527) of Basque‐Spanish bilingual 12–16‐year‐old students from the Basque Autonomous Community (Spain) participated in this study. The learners studied EFL as a third language at school and completed a written task about a disciplinary topic. Three EE‐related variables were measured: informal exposure, formal private tuition, and parental variables. Multiple regressions, Mann‐Whitney U tests, and correlations were used to explore potential differences related to the variables in writing performance. The analyses indicated that age was the strongest predictor, followed by both informal exposure and private tuition, while parental factors were non‐significant. Furthermore, EE effects interacted differently with age: private tuition had a stronger impact on younger learners’ scores but gradually diminished, while older learners showed greater gains from informal exposure, particularly from watching TV/films and social media. The study suggests that maturity is a crucial factor and that EE mediation effects need to be understood as a dynamic process. Pedagogical and theoretical implications are discussed to foster EFL learning inside and outside the classroom by considering maturational constraints.
Arias‐Hermoso et al. (Thu,) studied this question.