The Quick Answer
Leaving cookies and milk for Santa became popular in the United States in the 1930s, though older European customs left food for gift-givers' animals.
The Story
In some European traditions children left hay or treats for St. Nicholas' horse or Odin's flying horse. In America, during the Great Depression, parents encouraged children to share a little with Santa as a lesson in gratitude, and the cookies-and-milk custom grew.
Legend vs. History
The Depression-era 'lesson in gratitude' explanation is widely repeated but hard to prove exactly.
Tell the Kids
“Leaving cookies is a way of saying thank you to someone who works hard to make others happy.”
Did You Know?
In the UK and Ireland, mince pies and a glass of something warm are common. In Australia, some families leave a cold drink.
Try This Tradition
Bake one batch together and leave a carrot for the reindeer, too.