The study aims to explain the effectiveness of enriching students’ vocabulary acquisition through watching subtitle movies. Quantitative research with the quasi-experimental design is the research design in this study. The data were collected using pre- test and post-test. The research participants were 60 students of seventh graders of SMP H.Isriati Semarang. The data analysis in this study includes the statistical data from Spss and the statistical calculation. The data showed that the pre-test score for the experimental class is 60.2, and for the control class it got 54.7. An experimental class was given treatment using watching subtitle movies. While the control class was taught to use it without subtitles. The mean score from the post-test for the experimental class is 75.3 and for the control, class is 60.6. The statistical analysis showed the gained score for both classes that the experimental class was higher than the control class. And the data from spss showed that the Asymp. sig. (2-tailed) is 0,001 is smaller than 0,05 and the hypothesis was accepted. Besides that calculation, the researcher concluded that enriching students' vocabulary acquisition through watching subtitle movies was able to enhance the vocabulary of students at SMP H.Isriati Semarang.