This condition says it fits 12-36 months which seems like a very big size difference. I don't know how well they fit a 12 month old baby. My son who is 18 months is a size 5 and they fit perfectly. We switched to a size 6 shoe as thick socks and grips make it difficult to slip into a size 5 shoe. But overall the shock seems like great quality and my son hasn't slipped once since buying them. He's only had them a few days so hopefully they'll last a long time as the price of baby socks seems high.