From their website:
"The Canadian Naturalization databases contain references to about 200,000 people who applied for and received status as naturalized Canadians from 1915 to 1932. During that period, the Government of Canada published the lists of names of those naturalized subjects in the annual reports of the Secretary of State (Sessional Papers) and in the Canada Gazette. These two databases, produced by the Jewish Genealogical Societies of Montreal and Ottawa, make it possible to search those annual lists by name."
If you're not familiar with the Canadian Genealogy Centre, here's a great starting point: