Quaid and Buffington, 32, tied the knot Sunday in Montana, according to the actor's spokeswoman Cara Tripicchio. The site of the wedding was not disclosed.
Quaid's 12-year-old son, Jack Henry Quaid (search), stood as the best man, and the bride's attendant was her brother.
Quaid, 50, met Buffington in 2003 when a mutual friend introduced them at a dinner in Austin, Texas, Tripicchio said.
The actor was previously married to actress P.J. Soles. He also was married to actress Meg Ryan (search) from 1991 to 2001.
Quaid currently stars in "The Day After Tomorrow," (search) playing a scientist trying to prevent the end of the world when global warming unleashes disaster.