I went up a size from what my daughter is wearing in other Pediped styles, and still I can hardly get the velcro strap to extend all the way across the top of her foot to match the velcro on the other side.  She does have a high instep, and a rather "puffy" foot.  So if your child's foot is high or wide like this, know that the fit might be snug. (I can't go any larger in size, because the length is fine.)  Still, a very cute style, and wonderful Pediped quality.