Franco-Ontarians constitute the largest French-speaking community in Canada outside Quebec. According to the province of Ontario, there are 622,415 francophones in Ontario, making up 4.7 per cent of the province's population. However, the figure is derived from the province's "Inclusive Definition of Francophones" (IDF), which includes respondents from the 2016 Canadian Census who reported French as their mother tongue and respondents whose mother tongue was not French but have proficiency in the language and use it as their primary language at home. Prior to the introduction of IDF in 2009, a respondent's mother tongue was the main measure used by the government to determined the number of francophones in the province. There were 568,345 Ontarians, or 4.3 per cent of the population, that reported having French as a mother tongue in the 2016 census, making it the most common mother tongue in the province after English.
