The purpose of this study is to investigate the relationship between Vocabulary Learning Strategies (VLS) and vocabulary proficiency of high school students. In order to achieve this purpose, Schmitt (1997)''s VLS questionnaire and Gu & Johnson (1996)''s meta-cognitive strategies were administered to 100 high school students. After that, three types of vocabulary tests (Korean translation, receptive vocabulary knowledge, and productive vocabulary knowledge) were administered to the same students. SPSS (Statistical Package for the Social Sciences) 24 was employed to analyze the data, including cluster analysis, descriptive analysis, one-way ANOVA (analysis of variance), Pearson Correlation and T-test.
The findings of the study are the following:
1) Students preferred VLS such as ''Ask classmates for meaning'', ''Imagine words’ meaning'', ''Use dictionary'', ''Guess from textual context'' and ''Write new words repeatedly.'' The least preferred VLS are ''Use physical action when learning a word'', ''Use flash cards'', ''Use semantic maps'' and ''Put English labels on physical objects.'' This result is similar to that of Schmitt (1997). Mature learners do not think that some strategies such as using flash cards are very helpful.
2) There was a statistical difference mostly between advanced and beginner groups in using five strategy (determination, social, memory, cognitive, meta-cognitive) groups. However, there was no significant difference between advanced and intermediate groups in the five strategy groups. That is, once students reach the intermediate level, they do not put an effort to improve their VLS or they do not receive proper VLS instruction in class.
3) Three types of vocabulary tests showed a statistical difference among three vocabulary proficiency groups except for the productive vocabulary knowledge test for intermediate and beginner groups. Also, the average score of productive vocabulary knowledge test was significantly lower than that of the other two tests.
4) There was a statistical difference between genders in determination strategy (female students use it more than male students).
These findings provide the following implications:
1) Since some VLS are not used well by high school students as they grow older, teachers should consider students'' cognitive maturity and language proficiency when teaching VLS.
2) As there was no significant difference between advanced and intermediate students in using VLS, teachers should help advanced and intermediate students learn new and appropriate VLS for them to reach a higher level. As for beginner students, teachers should help them learn VLS mainly used by advanced and intermediate students so that they can be promoted to an intermediate level or higher.
3) Since there was a significant difference between genders in using determination strategies, teachers should help male students learn determination strategies in order for them to acquire vocabulary more effectively.
Finally, as five types of VLS were proved to be correlated to one another, teachers should help students learn various types of VLS. Also, they should consider the aspects of knowing a word (Nation, 2013) and teach receptive and productive vocabulary comprehensively.