Firanda, Nika. (2024). The Correlation between Students’ Vocabulary Mastery and Critical Thinking toward their Writing Skill. Department of English Language Education, Faculty of Tarbiyah, State Islamic Institute (IAIN) Kediri. Advisors: (I) Bahruddin, S.S, M.Pd. and (II) Annisa Aulia Saharani, M.Pd. Keywords: Vocabulary Mastery, Critical Thinking, Writing Skill. In writing skill, the writers require to have adequate vocabulary and critical thinking abilities to effectively arrange and express ideas. This research aimed at seeking If there is any significant correlation between three variables: (1) students’ vocabulary mastery (X1) writing skill of argumentative text (Y), (2) students’ critical thinking (X2) and writing skill of argumentative text (Y) , (3) students’ vocabulary mastery, critical thinking, and writing skill of argumentative text. In this study, the researcher used correlational design in quantitative research. The population of this research involves XI grade students of MA Ma’arif Udanawu, Blitar academic year 2024/2025. The researcher used random sampling to take the sample which is 127 students. The data were collected through vocabulary test, critical thinking test, and writing test. The data were analyzed using correlational statistic test namely Person Product Moment. The result shows that (1) there is significant correlation between students’ vocabulary mastery and writing skill with the coefficient correlation is .224, (2) there is significant correlation between students’ critical thinking and writing skill while the coefficient correlation is 0.294, (3) there is significant correlation between students’ vocabulary mastery, critical thinking, and writing skill with the R (coefficient correlation) is ,343. It can be indicated low correlation. Therefore, Ha is accepted and H0 is rejected.

FIRANDA , NIKA .   (2025). The Correlation Between Students’ Vocabulary Mastery And Critical Thinking Toward Their Writing Skill. IAIN Kediri