English, French, and Cree are the languages spoken by most metis people. Cree itself is the most dominant aboriginal language in Canada; spoken and utilized by almost 120,000 people from B.C. to Quebec and diversified into about a dozen dialects.
Historically, the form of Cree spoken by many metis was, in fact, a blending of French and (Plains) Cree dialect known as Michif. Use of Michif was more common prior to the 1900s. It's decline coincides with the period following the doomed Northwest Rebellion of 1885 and the earlier half of the 20th century; a time marked by the rise of native residential schools. It is well known that speaking one's native tongue was forbidden within these institutions. Studies indicate that the Michif language is in danger of extinction with fewer than 1000 people who can speak it fluently; virtually all speakers are over the age of 60.