The use of online social networking sites for educational purposes or expanding curricular opportunities has recently sparked debates in scholarly forums. This potential, however, has yet to attract sufficient attention in second language classes, and particularly in English as a Foreign Language (EFL) contexts. The current study explores the affordances of Facebook to help both improve EFL students' vocabulary knowledge and develop their vocabulary strategy learning in a blended learning course. To this end, a Facebook page was created to engage an intact class of first-year undergraduates (N = 25) majoring in English in a package of vocabulary learning strategies. The analysis of the data from Facebook content (i.e., the posts and comments shared throughout a semester) and a student focus group discussion revealed that students benefited from participating in different activities to improve their knowledge of English vocabulary and develop their awareness of various vocabulary learning strategies. The results, however, raised several concerns about the integration of Facebook into traditional pedagogy as a formal platform for language teaching and learning.