Abstrak
Project-Based Learning (PjBL) is a teaching method capable of increasing student participation through relevant and meaningful project activities. This study aims to assess the effectiveness of using Project-Based Learning on vocabulary mastery among ninth-grade students at SMPN 14 Tarakan. The method used in this study was a pre-experimental design with pre-tests and post-tests for a single group. The research subjects were students in Class IX-1, consisting of 31 students. The researcher collected data through vocabulary tests, including pre-tests and post-tests. The results showed a significant improvement after the implementation of the Project-Based Learning method. This was indicated by the Wilcoxon Signed-Rank test, which yielded a significance value of 0.001—lower than the 0.05 threshold—thereby rejecting the null hypothesis and accepting the alternative hypothesis. Additionally, the students’ mean score increased from 71.45 on the pre-test to 85.81 on the post-test. This study concludes that the implementation of Project-Based Learning has a positive impact on improving students’ vocabulary and can serve as an efficient and innovative alternative teaching method in English language learning.