From 1972 to 1989, he was Lecturer, then Reader, at the Science Studies Unit, University of Edinburgh, and, from 1989 to 2003, Professor of Sociology at the University of California, San Diego, before taking up an appointment at the Department of the History of Science at Harvard.
He worked as an instructor, then senior instructor, at the Science Studies Unit, University of Edinburgh, from 1972 to 1989. He later became a professor of sociology at the University of California, San Diego, until 2003, when he moved to Harvard's Department of the History of Science.