The purpose of the study was to examine the effects of comprehensionand production-based instructions on vocabulary learning of Korean elementary school students. A group of 24 students, 1st, 2nd, and 3rd grades, studying at the after-school English class, Gyeongi-do, participated in this study. The findings showed that both comprehensionand production-based instructions positively influenced Korean students’vocabulary learning. Specifically, the comprehension-based worked better on students' comprehension of the target vocabulary and production-based instruction positively influenced the production. The study also revealed the differences in terms of proficiency. As far as the proficiency levels were concerned, comprehension- and production-based instructions helped high levels develop understanding and production of the target vocabulary respectively, while both comprehension and production instructions positively influenced the comprehension of the target vocabulary of the low levels only, not the production. Lastly, high levels and female learners had in favor of production-based instruction while low levels and male students, comprehension-based instruction. The theoretic and pedagogical discussions were made based on the findings.