<![CDATA[This study was motivated by the low ability of elementary school students to write simple essays, a phenomenon suspected to be linked to limited mastery of Indonesian vocabulary. The study aimed to describe the level of Indonesian vocabulary mastery, describe the ability to write simple anti-bullying essays, and analyze the relationship between Indonesian vocabulary mastery and simple essay writing skills among third-grade elementary school students in Pesisir Selatan Regency. A quantitative approach with a correlational research design was employed. The study population consisted of 89 third-grade students from three elementary schools in Pesisir Selatan Regency; a saturated sampling technique was used, meaning the entire population served as the sample. Research instruments included a 30-item multiple-choice test to measure vocabulary mastery and a simple essay writing task using student worksheets. Data analysis involved descriptive analysis, normality testing, linearity testing, Pearson Product-Moment correlation analysis, and hypothesis testing using IBM SPSS 26. The results indicated that the data were normally distributed (Sig. = 0.141) and exhibited a linear relationship (Sig. = 0.559). The correlation analysis yielded a Pearson Correlation value of 0.402 with a Sig. (2-tailed) value of 0.000 (p < 0.05), demonstrating a significant relationship of moderate strength between Indonesian vocabulary mastery and simple essay writing skills among the third-grade students. The higher the students' vocabulary mastery, the better their ability to write simple essays.]]>
