In this study, the writer used a quasi-experimental non-equivalent-groups pre-test-post-test design. The subjects of this study were the second grade students of Elementary School. The writer used two classes as the sample of this experiment. The experimental group was taught using mind mapping and another was taught using word list. Before that, the writer gave a pre-test, and after the experiment a post-test to both groups. From the calculation of the t-test, the writer found the t-observation of both groups. From the analysis of the pre-test, the writer found out that those two groups had equal ability in vocabulary mastery. From the post-test scores, the writer also found out that those two groups were not significantly different. The t-observation of the two groups was 1.26, while the t-table was 2.08. It means that the null hypothesis which says “there is no significant difference between the vocabulary mastery of the second grade students who were taught by using mind mapping technique and one of those taught by using word list technique” was accepted.