|Family|| Doris (wife)|
- Typically, he sports a green sweater with red trim, blue pants and red shoes.
- In the winter (particularly when shoveling snow), he wears a puffy blue jacket.
- At rest time or nap time or bedtime, he wears green pajamas and red sandals.
Caillou's Promise: Caillou told his father he was playing and didn't want Rosie to play with him in the sandbox meaning that he waited for his mother to be gone so he can play in the sandbox alone and keep Rosie out if it, but Boris asked him if he remembers the promise he gave to Doris and promise to share the sandbox and he told him it's very important not to break a promise.
- At work, he wears blue jacket, white shirt, a paisley tie, khaki pants and brown shoes in All In A Days Work.
- Caillou the Chef: He reveals that he once worked at a pizza parlor.