This research aimed to find out how the Domino Card Game can improve students’ vocabulary mastery and classroom situation when domino card game is implemented to teach vocabulary mastery through domino card game with the eight grade students of SMP Negeri 03 Sungai Raya in the academic year of 2022/2023.
This research was conducted through class action research (CAR). The subject of this study was the study of SMP Negeri 03 Sungai Raya eight grade, consisting of 33 students. This research use observation and measurement techniques for data collection. The tools of data collection were observation
checklist and field note for the observation technique and vocabulary test for the measurement technique. Then, the data analysis in this research used qualitative analysis to analyze qualitative data and quantitative analysis to analyze quantitative data. The researcher used two types of scoring, which are individual scores and mean scores used to measure the students’ vocabulary mastery through domino card game.
The students were more active in following the vocabulary learning process used domino card game. Then, they more enthusiastic in the vocabulary learning process used domino card game. The use of domino card game could improve students' scores on the vocabulary test which could be seen from cycle 1 students' scores were low with a mean score of 75,36 and then students' scores improve in cycle 2 with a mean score of 81.36. So, the researcher suggested to the
other teacher who want to teach the students in vocabulary mastery using domino card game. Domino card game is appropriate method used to improve students’ vocabulary mastery and also interesting method in teaching and learning process.

Keywords: Classroom Action Research, Vocabulary Mastery, Domino Card Game.