Lexical knowledge is an important predictor of second language learning. The present study focuses on aspects of lexical knowledge of Korean elementary (6'h grade) and middle school learners (9'h grade) in connection to learni ng strategies, that is, with regard to vocabulary learning and by investigating the learners' preferred English medium of interest. The learners were asked to complete questionnaires for information on vocabu lary learni ng strategies, and were tested with receptive and prod uctive vocabulalY levels test to assess their vocabulary knowledge. One-way ANOVA was conducted to note differences between the different vocabulary learning strategy groups, and multiple regression was employed to select predictors of learners' receptive and vocabulary knowledge. While the learners did not favor public education (school lessons), private lessons indicated to be the dominant means of learning English among the 6th graders with larger vocabu lalY sizes; the use of the vocabu lary workbook indicated to be a useful resource for the 9th graders. Although movies were popularly viewed by most of the learners, it was tile learners who had been reading books in Engli sh that seemed t.o have obtained larger vocabulary sizes. The findings provide guidelines for vocabulalY instruction in Korean elementary and middle school contexts .