This study examined the effects of teaching contextual inference and word association strategies on 5th grade elementary school students' vocabulary knowledge development. A total of 56 students participated in the current study, as divided into either the contextual inference group or the word association group. The vocabulary proficiency levels of the participants were also considered and the students in each group were further divided into either the upper level group or the lower level group. The participants experienced six treatment sessions, and in each session they had to study five vocabulary items using each of the two vocabulary learning strategies. The posttest and delayed posttest results indicated that both strategies were effective for the vocabulary knowledge development of the upper level group as well as the lower level group. Some possible implications for elementary school English classrooms in Korea are discussed.