This study investigated (a) the lexical demands of academic spoken English and (b) the coverage of the Academic Word List (AWL) in academic spoken English. The researchers analyzed the vocabulary in 160 lectures and 39 seminars from four disciplinary sub-corpora of the British Academic Spoken English (BASE) corpus: Arts and Humanities, Life and Medical Sciences, Physical Sciences and Social Sciences. The results showed that knowledge of the most frequent 4,000 word families plus proper nouns and marginal words provided 96.05% coverage, and knowledge of the most frequent 8,000 word families plus proper nouns and marginal words provided 98.00% coverage of academic spoken English. The vocabulary size necessary to reach 95% coverage of each sub-corpus ranged from 3,000 to 5,000 word families plus proper nouns and marginal words and 5,000 to 13,000 word families plus proper nouns and marginal words to reach 98% coverage. The AWL accounted for 4.41% coverage of academic spoken English. Its coverage in each sub-corpus ranged from 3.82% to 5.21%. With the help of the AWL, learners with knowledge of proper nouns and marginal words will need a vocabulary of 3,000 and 8,000 word families to reach 95% and 98% coverage of academic spoken English, respectively.