The Relationship between Intermediate EFL Learners' Writing Performance and their Lexical and Grammatical Knowledge

Abstract This study examines the relationship between intermediate EFL learners' writing performance and their lexical and grammatical knowledge. While previous research has explored the individual effects of vocabulary and grammar on writing, few studies have investigated their combined influence. This study seeks to determine whether grammatical or lexical knowledge plays a more significant role in predicting writing performance. A sample of 100 Iranian intermediate EFL learners was selected based on their scores on the Cambridge Placement Test. Participants completed grammar and vocabulary assessments, followed by a writing task evaluated by two independent raters. Pearson correlation and regression analyses were conducted to measure the relationships among the variables. The findings revealed a significant correlation between both grammatical and lexical knowledge with writing performance, with lexical knowledge displaying a slightly stronger predictive value. This suggests that while grammar is essential for structuring coherent sentences, lexical knowledge is more influential in determining the overall quality of writing. The study supports previous research emphasizing the importance of vocabulary in second language acquisition, highlighting its role in enhancing learners’ writing proficiency. These findings have pedagogical implications for EFL instruction, suggesting that language teachers should place a balanced emphasis on both vocabulary acquisition and grammar instruction. Providing learners with extensive exposure to academic vocabulary, along with opportunities for contextualized grammar practice, may improve their writing proficiency. Future research could explore additional variables, such as cognitive factors or writing strategies, that may contribute to EFL learners' writing development.