The relative role of vocabulary and grammatical knowledge in L2 reading comprehension: a systematic review of literature

The purpose of this systematic review is to synthesize the findings in the literature on the relative contribution of two types of linguistic knowledge (i. e., vocabulary and grammatical knowledge) to L2 reading comprehension; and to discuss the possible factors that might have led to the complexity and incongruity of the research findings. Nineteen studies were identified for this review through a systematic process of selection, and were analyzed in terms of the relationship of vocabulary and grammatical knowledge with L2 reading comprehension and their relative significance. The result of this review showed that there was no clear evidence supporting which type of linguistic knowledge is more contributive than the other; and the inconclusive findings might be attributed to the variations in the design of the studies. Two factors emerged, including participants' language proficiency and construct definition, operationalization, and measurement. Some considerations for future research are suggested.