this study was an attempt to investigate and compare the effect of lexical inferencing and concept mapping on developing vocabulary retention of iranian language learners. sixty homogeneous students from different intact classes who were being taught as intermediate learners in sokhan english institute participated in this study. they were in different classes. a teacher made test as a pre-test was administrated to evaluate their knowledge about the selected words. pearson correlation showed a significance correlation between teacher-made test and pet test which administrated to select homogeneous participants. on the other hand, leven’s test verified the similar variances between two experimental groups. after treating two different strategies, another teacher made test, post-test, measured the participants’ vocabulary promotion and retention of the selected and taught items. the results of post-test pointed out that both groups had significant progress but the concept mapping group outperformed the lexical inferencing group.