This study used a randomized pretest-posttest control group design to examine the effect of the integration of corpora in general English courses on the students' vocabulary development. To enhance the learners' lexical repertoire and thereby improve their reading comprehension, an online corpus-based approach was integrated into 42 hours of reading comprehension classroom instruction. The results of the analysis of covariance (ANCOVA) revealed that the experimental group outperformed the control group on the posttest suggesting that the main effect of corpus integration has been significant. The findings both theoretically and practically provide hints for teachers, educational policy makers, and future researchers.