This thesis studies about vocabulary acquisition's strategies of English as second language. There have been so many researchers conducted research in language acquisition. Generally, linguists group the process of acquiring language into first language acquisition and second language acquisition. In addition, there is also term vocabulary acquisition which refers to the process of acquiring vocabulary. In fact, the term acquisition is interpreted differently by language researchers. Some researchers distinguish between acquiring and learning. On the other side, the other researchers assume those terms as the same. In this research, the researcher refers to the notion that those two are similar. The process of acquiring vocabulary is influenced by many factors. Some of the factors found by the language researchers are first language background, motivation, and learning strategies. Language strategies itself can be divided to some types. Researchers found various strategies in their research on language learning strategies. One of them is Shirahata et al. (1999, in Azumi, 2008) who devided learning strategies into direct and indirect strategies which each of them contains three sections. Azumi (2008), using language learning strategies initiated by Shirahata et al., found that strategies in learning vocabulary is more used by advanced students than intermediate and elementary students. By this research, the writer tried to look for the strategies that mostly used by students, their reason for using the strategies, and how the strategies influence them, which was not done in Azumi’s research. By the end of this research, the researcher found that the results were the most often used strategies by each subject in this research are Repeting and Using Music. Their reasons for choosing certain strategies were varied. Each of them was different based upon factors influencing each subject. And the last, the way each strategy takes role in vocabulary acquisition process is also depended on the subject who chooses it. Finally, the researcher hopes that the finding of this research can be useful for the development of science in language acquisition, especially in vocabulary acquisition, and help the readers who want to explore the lore of it
