The establishment of Catholic missions among the First Nations of Saskatchewan, like those of Manitoba and Alberta, did not come about as a result of a preconceived plan or strategy on the part of the Missionary Oblates of Mary Immaculate. The establishment, as well as the location, of these missions was a pragmatic response to circumstances and needs. To begin with, the Oblates were always short of human and financial resources: missions could not be established where it was convenient for the missionaries, but where the chances of a successful venture were highest. When the Saulteaux in the immediate vicinity of St. Boniface demonstrated little interest in Oblate efforts, the latter turned their attention to the Chipewyan of Île-à-la-Crosse, who were reported to be more receptive to the Christian message. In addition to a receptive audience, Oblate missions tended to be established at or near a Hudson's Bay Company post, where First Nations were accustomed to come to trade at seasonal intervals.
Alexandre-Antonin Taché and abbé Louis- François Laflèche were responsible for the establishment of St. Jean-Baptiste Mission at Île-à-la-Crosse in 1846. In time, this mission served as a strategic central base for the expansion of the missionary frontier, as missionaries visited Lac La Ronge, Reindeer Lake, Cumberland, Pelican Lake, Portage La Loche, as well as Fort Chipewyan on Lake Athabasca, which became the main base for the establishment of missions in the Mackenzie Basin. In this early period of the expansion of the missionary frontier in the northern and central regions of what is now Saskatchewan, other missions were established at Green Lake and Battleford (1875), Onion Lake and Cumberland House (1877), and Pelican Narrows (1878). In the meantime, with the exception of accompanying Métis buffalo hunters, there was little missionary activity in the southern regions. In 1865, Bishop Taché visited the Qu'Appelle Valley and selected the site for St. Florent Mission for the purpose of facilitating the instruction of the large number of Métis resident in the region and the dispensing of sacraments to them. From Lebret, Joseph Lestanc, Jules Decorby and Joseph Hugonnard accompanied the hunters in their camps in Willow Bunch, Wood Mountain, and the Cypress Hills. After 1870 a large number of Métis left Manitoba and settled in the Duck Lake region, and permanent missions were founded at St. Laurent de Grandin (1871), Duck Lake (1877), and St. Louis de Langevin (1885).
The decline of buffalo and the signing of treaties with the Plains tribes necessitated a change in Oblate strategy and a consolidation of their missionary efforts. Since there was a definite advantage to being located on or near a reserve, some missions were relocated and new ones erected. Early schools built by the Oblates in their missions, and those established later by the federal government and confided to the jurisdiction of the Oblates, became extensions of their frontier “parish.” Through practical education the Oblates hoped to continue and enhance their apostolic and missionary efforts, and simultaneously prepare the First Nations for the changes necessitated by the end of the old order based on the buffalo hunt. The advance of settlement created additional responsibilities for Oblate missions, which henceforth would have to minister to the needs of settlers until regular parishes were erected and staffed with a resident clergy. The first mass in Regina, for example, was celebrated in 1885 by Pierre Saint-Germain, an Oblate stationed in Willow Bunch. The settlement era imposed incredible linguistic demands on missionaries because of the polyglot nature of the newcomers, and increased the labours of the missionaries because the immigrants were spread out over large areas of the province. From Fort Ellice, near the Manitoba -Saskatchewan border, Jules Decorby initially ministered only to the Indians and Métis but, when settlers began to arrive in the region in the 1880s his ministry took him as far as Swift Current and, in these travels, he laid the foundations for future parishes in Lestock, Marieval, St. Philippe, Moose Jaw, and Swift Current. Itinerant missions among newly arrived settlers were gradually replaced by permanent parishes that served outlying or frontier areas. While the Oblates continued to assume responsibility for the First Nations missions, secular clergy were arriving in larger numbers to serve as pastors in the settled areas. The erection of the Diocese of Regina in 1910 was indicative of a maturing Catholic establishment in Saskatchewan.