This thesis explores two Québec's Irish questions: the first pertains to the survival of the ethnic sentiment of Irishness in the province of Québec at the beginning of the XX th century; the second looks at the impact of the political question of Ireland in Québec, between 1898 and 1921. The social, political and cultural upheavals that occurred in Ireland between 1898 and 1921--leading to the partition of the island and to the creation of the Irish Free State and of Northern Ireland--, were of concern to both French-Canadians and Irish-Catholics of Montréal and Québec City. It is no coincidence that the political question of Ireland had some impact in those communities. For numerous Irish-Catholic descendants of Québec, ±feeling Irish» and identifying themselves as full-members of the provincial Irish-Catholic community, encouraged them to stay in touch with the events occurring in Ireland. The survival of Irishness would lead many of them to actively support the struggle for Irish autonomy by investing both their time and money into the cause. For numerous French-Canadians, the rise of Home Ruler or Sinn Féiner nationalism in Ireland would also echo the rise of French-Canadian political and cultural nationalism. Members of these two communities, active in the Vieille Capitale and in the Canadian metropolis of the time, then worked--sometimes jointly, sometimes independently--, for the ambiguous cause of the ±liberty of Ireland». However, various tensions between Irish-Catholics and French-Canadians, in the province of Québec as well as in Canada, prevented the reconciliation of these important Catholic communities of Québec. While the Irish question helped to foster a better understanding of each other, the internal divisions concerning different questions (such as the political future of Canada, or the use of the English language in Canada's parishes and schools) would continue to create animosities between these two Québec coreligionists.