Marguerite had survived many threats in the twenty-six years she had been in wilderness of Canada. She had lived through Iroquois attacks, a fire that destroyed her small village, plagues on the ships that she took back and forth to France, but nothing threatened her dreams and hopes more than what her own bishop said to her in 1679. He told her that she had to join her Congregation of Notre Dame with its teaching sisters to a cloistered religious order of Ursulines. But Marguerite had overcome many challenges to get to this day and was not deterred. In her own native France, she had belonged to a group of women who cared for the sick.

The stories of hardships and dangers in Montreal that made other people shiver had awakened a call from God in her to serve the Native Americans and settlers who endured this adversity. She met with the governor of what was then called Ville Marie and convinced him she was the person he was looking for to help start a school for the children of Montreal. When she arrived in Ville Marie, as it was called then, she found that few children survived to school age. She helped the remarkable Jeanne Mance, who ran the hospital, to change this tragedy. When she finally had children to teach, she had to set to up school in a stable.

Her Congregation remained an active teaching order, one of the very first of its kind for women. Their rule had to go through one more attempt at turning them into a cloister but Marguerite lived to see the triumph when their Rule was made official in 1698. She was canonized in 1982 by Pope John Paul II.