The thesis was entitled The Effectiveness of Round Robin Teaching Method to Enhance Students’ Vocabulary Mastery (An Experimental Research at the Tenth Grade Students of MA Walisongo Pecangaan Jeparain the Academic Year of 2018/2019). In this study, the writer conducted a research aimed to know the effectiveness of Round Robin teaching method to enhance student’s vocabulary mastery at tenth grade of MA Walisongo Pecangaan in the Academic Year of 2018/2019. In order to achieve the objective of this study, the writer used quasi experimental research using pretest, posttest, experimental group and control group. The population of this study was tenth grade of MA Walisongo Pecangaan Jepara. The sample of this study was class X MIA 1 and X MIA 2. The numbers of the student were 44 students. There were four meeting during experiment. Before the experiment was conducted, the students were given a pre-test than they were given a post-test. The result of this study showed Round Robin teaching method gave significant results between the student who were taught Round Robin teaching method and the students who were not taught Round Robin teaching methodafter giving treatment in experimental and control group. It could be seen that the post-test score were better than pre-test score. The average of experimental group was 40,63636 (pre-test) and 88 (post-test) and the average for control group was 45,72727(pre-test) and 60,63636 (post-test). Moreover, the result of t-test is 0,62119 and the writer uses the degree significant of 5% and 1%. It can be seen that on df22 in significant 5% and 1% the value of degree are 0,4044. It can be concluded that the t-test > t table. It means that the result from this calculation 0,62119 > 0,4044. Based on the result, the writer conducted that by Round Robin teaching method was an effective method to enhance students’ vocabulary mastery at MA WalisongoPecangaanJepara in the Academic Year of 2018/2019.