<![CDATA[This study aims to determine the effectiveness of the Task-Based Learning (TBL) approach in improving students’ vocabulary mastery at STT Obaja Jakarta. This research was motivated by the fact that many students at STT Obaja still had limited vocabulary, which hindered their ability to communicate effectively in English, understand reading texts, and participate confidently in classroom activities. This study employed a quantitative research method with a Pre-Experimental Design, specifically the One-Group Pretest-Posttest Design. The population of this study consisted of 64 students of STT Obaja Jakarta, and since the population was relatively small, the Total Sampling (Saturated Sampling) technique was applied, resulting in a total sample of 64 respondents. Data were collected through a vocabulary pretest and posttest and analyzed using IBM SPSS Statistics. The results showed that the students’ mean vocabulary score increased from 68.33 in the pretest to 77.39 in the posttest, indicating a mean gain of 9.06 points. The Shapiro-Wilk normality test produced significance values of 0.848 (pretest) and 0.299 (posttest), both greater than 0.05, indicating that the data were normally distributed. The homogeneity test showed a significance value of 0.194 (> 0.05), indicating homogeneous variance. The Paired-Samples t-Test showed t(63) = -10.549 with p < 0.001, which is lower than the significance level of 0.05. Therefore, the null hypothesis (H₀) was rejected and the alternative hypothesis (H₁) was accepted, indicating a statistically significant difference between students’ vocabulary mastery before and after the treatment. It can be concluded that the Task-Based Learning approach significantly improved students’ vocabulary mastery at STT Obaja Jakarta.]]>
