He has taught applied linguistics, TESOL and EAP at institutions in New Zealand, the United States and Singapore. His main research interests are in assessing second language vocabulary and the testing of English for academic and professional purposes. He is the author of Assessing vocabulary (Cambridge, 2000) and was co-editor of Language Testing from 2002 to 2006. He is currently Vice-President of the International Language Testing Association and will serve as President in 2011-12.