After his seminary training he taught at Valleyfield College, then the University of Montreal, where he edited a monthly journal titled "Action Française". He also developed a Quebec history curriculum that ignored the fact that France chose to keep Guadaloupe and surrender Quebec to Great Britain in the Treaty of Paris of 1763. Instead, he always referred to King Louis XV's decision as a conquest of Quebec by the British, and called the Canadian Confederation of 1867 a disaster. Lionel Groulx espoused the theory that Quebec's only hope for survival was to foster a Roman Catholic Quebec as a bulwark against English power.
A controversial figure, he was denounced by the English press in Canada and the United States for his anti-Semitic statements and his support of the Nazis in Germany in numerous 1930s articles in Montreal's Le Devoir newspaper.
Lionel Groulx's major writings are "Histoire du Canada Français" (1951), and "Notre Maître le passé."
Groulx founded l'Institut d'Histoire d'Amérique Française in 1946. This small institute is located in Montreal, Canada. It is devoted to the historical study of the French presence in North America and the publication of La revue d'Histoire de l'Amerique Francaise, which Groulx founded in 1947.
Professional Historians of all languages and all countries who are interested in the History of the French presence in North America regularly read and contribute to the revue d'Histoire de l'Amerique Francaise. They participate by writing scholarly texts for it or by holding active positions in its peer review committees.