[1] Montpetit was elected to the Montreal Catholic School Commission in 1994 as a candidate of the secular and progressive Mouvement pour une école moderne et ouverte (MÉMO).
[4] Throughout her time as a school commissioner, Montpetit was involved in efforts to provide a proper schoolyard space for the École Charles-Lemoyne, in her division.
In 2002, Montpetit argued that the Tremblay administration was underfunding Montreal's older communities relative to newly amalgamated suburban wards, adding that her area was having difficulty paying for essential maintenance.
After some local residents indicated their disapproval of the statue, Montpetit noted, "There is always a shock with modern art but if people take the time to appreciate it they will come to see this is good.
"[8] By 2004, Montpetit and fellow Vision Montreal city councillor Robert Bousquet were often engaging in heated battles at the borough council level.
[13] She also helped facilitate a revitalization project for the Lachine Canal,[14] and in September 2009 she announced plans to rename Campbell-Centre Park in the Little Burgundy neighbourhood after jazz legend Oscar Peterson, who had grown up in the area.