Vocabulary mastery is crucial in enhancing students’ writing ability, particularly in composing descriptive texts. Writing requires a sufficient vocabulary range to express ideas effectively and coherently. However, many students struggle with writing due to their limited vocabulary knowledge. This study investigates the correlation between students’ vocabulary mastery and ability to write descriptive texts among seventh-grade students at SMP Negeri 26 Banjarmasin in the academic year 2023/2024. Understanding this correlation is essential for improving students’ writing performance and for developing more effective teaching strategies in English language learning.

This research employs a quantitative correlational method to examine the relationship between the two variables. The study involved 32 students selected through purposive sampling. Data were collected using a vocabulary test and a descriptive writing test. The results were analyzed using Pearson Product-Moment correlation to determine the strength and significance of the correlation. The findings indicated that the mean score for students' vocabulary mastery was 91, categorized as an excellent level. Meanwhile, the mean score for their writing ability was 77, which is a good level. The analysis yielded a correlation coefficient of 0.968. At a 5% significance level, the critical value (rtable) was 0.361, resulting in r > rtable (0.968 > 0.361). The findings revealed a positive and significant correlation between vocabulary mastery and descriptive writing ability, indicating that students with higher vocabulary knowledge tend to perform better in writing tasks.

Based on these results, it can be concluded that vocabulary mastery significantly influences students' writing skills. The better the students’ vocabulary knowledge, the more effectively they can express their ideas in writing. These findings suggest that teachers should implement vocabulary-enriching activities to improve students’ writing performance. Additionally, further research is recommended to explore other factors affecting students' writing abilities, such as grammar proficiency and reading comprehension skills.