Yunjung Ku
ABSTRACT Second language acquisition research has largely emphasized language development, often overlooking language maintenance following international mobility. Addressing this gap, the present longitudinal mixed‐methods study examined oral proficiency maintenance among foreign language (FL) learners 9 months after returning from residence abroad. Data were collected from 22 Korean learners through questionnaires, elicited imitation tasks, and semi‐structured interviews across three time points. Quantitative analyses revealed that learners largely maintained their oral proficiency over time. Initial proficiency strongly predicted final performance although it was not associated with the magnitude of developmental change. At the same time, overall post‐return FL use did not significantly predict proficiency outcomes. Additional exploratory analyses revealed that language maintenance was supported by technology‐mediated extramural language learning, particularly input‐rich reading activities. These findings highlight the role of accessible, input‐rich practices in sustaining oral proficiency after immersion and offer implications for post‐mobility program design and learner support in non‐immersion contexts.