This study examined the effectiveness of integrated language instruction using dictogloss on vocabulary knowledge and retention. Forty EFL students from two classes of an elementary school participated in the study. The integrated language class and segregated language class were examined by looking into the effect of each instructional type on the vocabulary knowledge development and retention. A total of 10 target words were selected from a storybook related to their textbook. Four types of vocabulary knowledge were measured: passive recognition, passive recall, active recognition, and active recall. The pretest and posttest were performed to measure the vocabulary growth. The retention rate of each instruction was examined by conducting a delayed posttest on the same words after two weeks. The results of this study indicate that integrated language instruction using dictogloss works better in vocabulary retention. They also suggest that further classroom research is required to prove that dictogloss is an effective way for vocabulary learning.