The daughter of Joseph Gagné, master pilot, and Luce Mercier, she was born in Saint-Michel and was educated there.
She returned to Quebec City in 1880 and was sent to the Lac Saint-Jean region in spring 1882; her mission was to found a monastery at Roberval to encourage religious vocations and educate young girls.
Gagné adjusted the curriculum to meet local needs, educating young women in farming and domestic science.
[1][2][3] Gagné worked closely with the Quebec Department of Agriculture and Colonization to maintain her curriculum and she also served as an advisor to local farmers.
At the time, the Le Progrès du Saguenay reported that Gagné's life "was part of the history of the region".