Purchased a 6-12 mos size for my then 5 month old and he was able to wear it for maybe a month before the head opening was too small. My little one is on the low end of the growth percentile chart and his head is proportional. However, the torso and arms fit well. While I agree that this is a super cute outfit, functionally it didn't work because of the small head opening. Maybe if there were snaps on both sides it would be much easier on and off but doesn't work unless I order a much larger size which would probably be too big. This adorable outfit is 100% cotton so it's possible that I shrunk it in the wash. The care instructions indicate cold water wash but I may have used warm. Overall, a super cute outfit if your little one's head fits through the opening.