Born in Montreal, Denise had received a good education in a non-religious academy and knew English, singing and music well. She entered the community of Montreal in August of 1874, but she was immediately named to Saint-Basile where, at her asking, she would remain for the rest of her life. Sister Thériault was above all in charge of teaching French and music, of writing the annals and dealing with the correspondence. For eighteen years, she was assistant to the Superior. According to Sister Maillet, this devoted sister deserved to be considered as one of the founders of their House in Saint-Basile.