From 1982 to 1987, he held research positions at the Institute for Advanced Study at Princeton, Concordia University, and the Tata Institute of Fundamental Research. In 1987, he was appointed as Associate Professor at the Downtown campus of the University of Toronto, and 1991 he was promoted to Full Professor. In 2001, he was deputed to the Mississauga campus to serve a two-year term as Associate Chair of Mathematics, and from 2004 to 2007 he served as the inaugural Chair of the newly-created Department of Mathematical and Computational Sciences at the Mississauga campus. Twice he was Chair of the Department of Mathematics at the University of Toronto Downtown campus (2008-2013 and 2014-2017).
