Based on the books by Christine L'Heureux, the show centers on a 4-year-old named Caillou, a bratty preschooler who is upset by the world around him. He has many crying tantrums with his family and friends and uses his whining in every episode, but in the end he's just as curious as any four-year-old kid would be, and loves learning all about how the world works.

Caillou celebrated it's 25th Anniversary of Books and TV Series.