Ignace Bourget was born on October 30, 1799 in St-Joseph-de-Lévis; the son of Pierre Bourget and Thérèse Paradis, “inhabitants”, according to the term of the time, well-rooted in their land and their faith. He was the eleventh child in a family of thirteen.

In 1811, he entered the small Séminaire de Québec. During the seven years of his studies in this institution, he was noticed for his faithful attitude and his great piety.

Admitted to the Grand Séminaire de Québec, he was tonsured on August 11, 1818 and then, a month later, directed to the Nicolet seminary. There he spent three years teaching Latin while simultaneously continuing his theological training.

In January 1821, Msgr. Joseph-Octave Plessis of Quebec appointed him secretary to Msgr. Jean-Jacques Lartigue, who had just been made auxiliary bishop of Quebec for the district of Montreal. One year later, Ignace Bourget received priestly ordination in the chapel of the Hôtel-Dieu from Msgr. Lartigue. During the nineteen years or so during which he worked alongside Msgr. Lartigue as secretary, vicar general, and then coadjutor bishop, he was a reliable disciple, a faithful friend, a confidant, and a close collaborator. The influence of the first bishop of Montreal certainly marked the episcopate of the second.

Thus, the day after his ordination, Msgr. Lartigue asked Abbé Bourget to see to the construction of the Saint-Jacques church, of which he later became chaplain, just as he entrusted him with the direction of the twenty seminarians housed in the episcopal house adjoining the cathedral.

During the decade from 1825 to 1835 in particular, Ignace Bourget joined in the struggles carried by Msgr. Lartigue, participating in his fatigue, his worries, and his humiliations.

The secretary, who became vicar general in 1835, received from Msgr. Lartigue the episcopal ordination as coadjutor bishop with a future preferment on July 25, 1837 on the feast of Saint James the Greater. For three years, Msgr. Ignace Bourget made a special effort to visit the parishes of such a vast diocese.

The death of Msgr. Jean-Jacques Lartigue on Easter Day, April 19, 1840, deeply affected him.