Advancing quickly in the religious and social hierarchies, it was but a matter of time before Saint-Vallier would be elevated to the rank of bishop. In 1685, Mgr de Laval, Bishop of Quebec, gave his resignation to the King and proposed Saint-Vallier to replace him. His entourage first pushed him to refuse the see, since the Diocese of Quebec was relatively new, poor, far from court and at that time "perhaps the most wretched and difficult of all the dioceses in mission lands". Abbot Saint-Vallier finally decided to accept the position, and left France for a sojourn in his future see with the title of vicar general of Bishop Laval, since the ceremony of his investiture had to be postponed due to the difficult relationship between the Pope Innocent XI and Louis XIV.