The Caillou television series was based on the popular book series originally written in French by Christine L'Heureux and illustrated by Hélène Desputeaux. The book series was introduced in 1987 by book publishers, Les Editions Chouette with the television series launched in 1998. The word 'Caillou' means pebble or stone which can most likely explain why Caillou is bald.