The role of vocabulary knowledge in EFL proficiency

Abstract

This research synthesis explored the role of vocabulary size/breadth, and depth/quality of vocabulary knowledge in reading comprehension, writing quality, speaking fluency and listening comprehension. The aim of this study was to analyze to what extent vocabulary size and depth influence EFL learners' performance in the four macro skills in order to get a better understanding of the role of vocabulary knowledge as one of the main components of English proficiency. For this purpose, 15 empirical studies published since 2000 and that analyzed the two dimensions in English as foreign language were selected. This paper thus covers recent developments from a wide range of perspectives focusing on proficiency level and L1 background. Findings revealed that (1) vocabulary breadth and depth contribute strongly to EFL learners' performance at any proficiency level, (2) both the impact of breadth and depth on EFL proficiency are distinctive on each skill and key in language performance, and (3) emphasis should be placed on vocabulary acquisition in EFL classrooms, particularly on aspects such as (a) teaching and learning high frequency words and (b) word learning quality.