My 20-month old child does have big feet but these 2-3Ts still are too small after a few washes (heel of sock not covering son's heel).  They also pill and don't provide enough traction for my toddler jumping skidding hurtling on hardwood floors. I do prefer cotton but I am preferring the um, Asian-branded polyester socks with 50 traction dots on the sole and fun colors and patterns.