We have two boys 4 & 7 that needed new sweaters...Southpole has always been a brand we love and buy, as their clothes are such higher quality than any we can find elsewhere and they last forever. They grow out of them before they wear out and they still look new years later with 1000 washes. Amazon sizing is not true to Southpole...Southpole sizing is S (4) Med (5) Large (6) XL(7) Wider but not longer than a 6. Hope this helps! We had to exchange a few in order to get it right. It will shrink in the wash though so if you have a kid on the cusp order a size up. Our 4 year old fits in the medium with a little room and our 7 year old is in a Large...its a bit short but he's too skinny to bump up to the 8-10 it was swimming on him.