The present study was conducted in the context of learning English as a Foreign Language (EFL) with the purpose of assessing the roles of breadth and depth of vocabulary knowledge in academic listening comprehension. The Vocabulary Size Test (VST, Nation & Beglar, 2007) and the Word Associates Test (WAT, Read, 2004) were administered to measure breadth and depth of vocabulary knowledge, respectively. EFL listening comprehension was measured with an academic version of the International English Language Testing System (IELTS). The findings indicated that (a) both dimensions of vocabulary knowledge were positively and significantly correlated with academic listening comprehension, but depth of vocabulary knowledge indicated a higher correlation; (b) multiple regression analysis revealed that depth of vocabulary knowledge was a stronger predictor of listening comprehension success; and (c) a lexical coverage of 98% only yielded a listening comprehension percentage of 66.4%, which is less than the level of adequate listening comprehension, defined as scoring higher than 70% (Staehr, 2009). Although the present study confirmed the important role of vocabulary knowledge in successful EFL listening comprehension, other linguistic or non-linguistic factors might also affect the participants' listening comprehension success.