Born and raised in Montreal, William holds a Ph.D. from Yale and has taught economics at McGill since 1977. He served as Department Chair from 2005 to 2010.
In 1997, he took a 21-month leave from McGill and served as editorial pages editor of the Ottawa Citizen. His 1998 book, Globalization and the Meaning of Canadian Life, was runner-up for the Donner Prize for best Canadian policy book of the year. He writes on economics and other matters weekly in the National Post and every other week in the Ottawa Citizen. In 1989, a story of his in Saturday Night magazine won the National Magazine Awards Gold Medal for humour.