These are great quality boots. I read all the other reviews before buying and I'd definitely size down. My son wears a toddler 5.5 and I ordered him the 5 (the smallest size offered) and they are still big on him. They'll definitely last him a long time. Sturdy soles, too, so he'll outgrow them before he wears them out!

Update: March 2014: These boots have been worn almost daily for a year. Just last month one of the loops at the top broke off and a small hole formed on the top of the foot. These boots have seen so much wear that I am impressed at how well they have held up. I would definitely buy this brand again. (Also, the size 5 still fits, although a little tight now, a full year later. I will say that my son's feet haven't grown that much since, so that definitely helped us get the most out of them.)