One of the most entertaining things to do for a child is to go out and do something he's never done before and since many kids don't remember trick or treating when they're an infant, but by the time they're ready to get into toddler Halloween costumes, it's a good bet that those kids are ready to pick out their own costumes and have a small amount of say in just how they'll be dressed up. It's always a good idea to make sure that kids know how to be safe during Halloween and a safety talk after picking the costume is a good idea.