The main purpose of this research was to find out the effectiveness of Domino Game to enrich Vocabulary at the first grade students of SMP Negeri 5 Purbalingga in Academic year 2015/2016. This was s quasi experimental research. There were two classes, which became the experimental class and control class. In collecting the data, pre-test and post-test were used to find out the effect of the treatment that was given to experimental class and control class. Both test consisted of 30 items multiple choices. To analyse the data, t-test was used to get the result of the treatment. Based on the data analysis of pre-test and post-test,the t-test result was 3.189 and the result of t-table at the significant level 0.05 with d.f 66 was 2.00. The calculation of t-test with t-table was concluded that t-test was higher than t-table (3.189>2.00). Thus, it can be concluded that Domino Game gave good effect to enrich Vocabulary.