Glosses have been assumed to be effective for developing vocabulary. This article discusses a within-subject quasi-experiment which investigated the relative effectiveness of four vocabulary gloss types: L1 gloss, L1 gloss with phonological guidance, L2 gloss, and L2 gloss with phonological guidance. The participants were 63 Iranian undergraduate EFL students. The results of the post-test indicated that L1 and L2 glosses (conditions 2 & 4) accompanied with phonological guidance resulted in better performance in learning the target words irrespective of the language used in the glosses. Based on the findings, it can be assumed that phonological awareness can enhance the participants' understanding of the target words because of their representation in the phonological working memory. As such, language teachers are recommended to draw learners' attention to all aspects of learning vocabulary including meaning, orthography, and pronunciation.