An Investigation of EFL Students’ Vocabulary Size and Level at an Indonesian Private Tertiary Institution

Abstract. Having good vocabulary knowledge is essential for every student who learns a new language. However, there are only limited previous research projects which have studied the development of English language students’ vocabulary knowledge. Thus, this current study investigated English students’ vocabulary progress of participants who studied at a private tertiary institution in West Java, Indonesia. The participants came from three batches: 2018, 2019, and 2020 to find out the difference of development of vocabulary among them after studying English for two semesters. In its investigation, this study used two different instruments: the Vocabulary Size Test and the Vocabulary Level Test which respectively were created by Nation & Beglar (2007) and Webb et al. (2017). The findings show that after two semesters, the most improved vocabulary size occurred to participants from batch 2019.  On average, the vocabulary size achieved after two semesters is enough to read more advanced texts. However, the average score of their vocabulary level test shows that the high-frequency words were not yet mastered, with a decrease on the average score of 2020 students. The finding might imply that there should be more intervention in the teaching and learning of high-frequency words.Keywords: EFL Students, Vocabulary Size, Vocabulary Level