In 1985 Thibodeau-DeGuire joined the staff of École Polytechnique of Montréal, first as assistant to the president, then in 1986 she became director of public relations. In December 1989, she was responsible for the institution's communication when the École Polytechnique massacre took place. The school president and director were in Europe and Thibodeau-DeGuire showed admirable leadership throughout the crisis and in the organization of commemorative events and outreach which followed.