We love these socks! I ordered size S (1-3Y) when my toddler was 2 and wore size 6/7 toddler shoes. I have now ordered M (4-7Y) for size 10 toddler shoes wearing a 3 year old and they fit perfectly with little room to grow. This size was a bit tight for my 6 year old who wore size 1-2 kids shoes. I buy these socks for all my kids and they breathe reasonably well and provide enough cushioning and comfort for all year round but especially good for cold weather. I also like the variety of colors included in each pack, not too masculine or feminine, so they're great for crafts :) Also, the woven skeins get a little tangled, but the fibers tend to cling more with each wash, it seems to be real so they last longer despite looking a bit like an old sweater. I bought these and another brand of wool socks at the same time for one of the babies and the other brand didn't develop large holes until a few weeks after purchase. So far only a sock or two has torn a hole in this brand and we have had them for about a year now and this is the sock we choose almost every day. :) I have photographed (top to bottom) a new medium size pair, a one year old small size pair and a new small size pair so you can see the wear and tear.