ENGLISH:
This study addressed the main problem of low vocabulary achievement among eighth-grade students at Ponpes Uwais Alqorni Tempilang. The students particularly struggled with understanding and using vocabulary in context due to limited teaching methods, lack of motivation, and insufficient feedback. The purpose of this study was to investigate whether the use of the Multiple-Slot Substitution Drill (MSSD) method could significantly improve students’ vocabulary achievement. The study aimed to identify both the implementation process and the effectiveness of the method compared to traditional teaching approaches. The research employed a quasi-experimental design with a non-equivalent control group. Two classes were selected purposively: Class VIII B as the experimental group and Class VIII A as the control group. Data collection techniques included pre-tests, post-tests, observation, and documentation. To analyze the differences in students' performance before and after the treatment, the researcher applied both an independent sample t-test and a paired sample t-test using IBM SPSS Statistics. The findings indicated a significant improvement in vocabulary scores for the experimental group. The mean score increased from 51.76 (pre-test) to 76.47 (post-test). In the paired sample t-test, the sig. (2-tailed) value was 0.000, which was less than the significance level of 0.05. This result showed a statistically significant difference in students' vocabulary achievement before and after being taught using the MSSD method. Meanwhile, the control group showed a smaller improvement, with a pre-test mean of 57.22 and a post-test mean of 63.33. The result of the independent sample t-test comparing the post-test scores between the two groups showed a t-obtained value of 4.017, which was higher than the t-table value of 2.035 (df = 33), indicating a significant difference between the experimental and control groups. In conclusion, the implementation of the Multiple-Slot Substitution Drill method significantly improved the vocabulary achievement of eighth-grade students at Ponpes Uwais Alqorni Tempilang. This method proved effective and is recommended as an alternative vocabulary teaching strategy to support active learning and retention