In 1905, Tétreault took religious vows for the first time and the religious name of Mother Marie of the Holy Spirit. In 1909, the first six Sisters of the new congregation left for Canton, China. Within a short time, several convents opened throughout Quebec to provide support for the missions of the congregation. In 1920, they launched a missionary review, "Le Précurseur". On 2 February 1921 the school of formation for the foreign missions began to operate. By 1933, the foundress had established 36 communities of the Missionary Sisters in Canada, China, Japan and the Philippines.