Development of academic vocabulary knowledge during English-medium instruction

Journal article, 2025

In many contexts of English-medium instruction (EMI), the development of English language proficiency is an often-hoped-for outcome. Existing EMI research measuring English proficiency development reports gains in specific areas of English but not others. This study examines the growth of academic vocabulary knowledge among tertiary-level students studying in EMI. Academic vocabulary is crucial for effective academic communication, not least reading, and serves as a significant predictor of academic achievement. Hence, investigating its development is pertinent. The study was guided by three research questions: (i) What is the size of tertiary-level EMI students’ receptive (reading) academic vocabulary?; (ii) Does their academic vocabulary knowledge develop over time?; and (iii) if so, do certain students experience more development than others? A small longitudinal sample of EMI students enrolled in MSc programs in Sweden took a test of receptive academic vocabulary knowledge during the first and second year of their studies. Considerable variation in academic vocabulary size was observed. Some students had small academic vocabularies sizes, potentially impacting their engagement in academic tasks. Significant gains in receptive academic vocabulary knowledge occurred. The greatest vocabulary development was observed for those students who initially had smaller academic vocabularies. Implications are discussed for EMI learning environments.