The objective of this study was to investigate the correlation between vocabulary mastery and reading comprehension of seventh grade students of SMP Islam Al-Azhar 29 BSB Semarang. This research method is quantitative with a correlational approach. The sample of this study consisted of 29 students of class VII A. The research instruments used were vocabulary tests and reading comprehension tests, each consisting of 20 multiple-choice questions. Yielded scores were analyzed using Pearson Product Moment correlation. Results indicate Mean vocabulary proficiency score: 65.6/100 (range: 30-95) Mean reading comprehension score: 70.6/100 (range: 40-100) Significant positive correlation (r = 0.74, p < 0.05) Vocabulary contributes 54.76% to reading comprehension. The results showed that there was a significant positive relationship between vocabulary mastery and reading comprehension with a correlation coefficient of 0.74. In addition, the contribution of vocabulary to reading comprehension was 54.76%. The study confirms a strong positive correlation between vocabulary mastery and reading comprehension, emphasizing vocabulary's significant impact on reading skills.