I was hesitant because of the other reviews about being difficult to get onto the foot.  So I ordered one size up (which I do for any shoe expected to be warn with heavy socks, anyway) and they went on my 18 month old's foot just fine.  He wears a 5.5/6 normally, so I ordered a 7.  The inside sole is just rubber, but we live in the snow, so he's wearing heavy wool socks anyway.  Not only was it not difficult to get these cute boots on- it was easy!