100% Cotton! These are 100% cotton and nice and thick like the old-fashioned brands - not like the supermarket kind. Stretchy for easy dressing. You'll love them. Comfortable elasticized waist. True to size. Double stitched for extra durability. Made of 100% ringspun interlock cotton for extra softness. Made in England. Age/Size Weight Height 0-3 Months 10 lbs. 19-22 inches 3-6 Months 14 lbs. 22-25 inches 6-12 Months 18 lbs. 25-28 inches. 12-18 Months 22 lbs. 28-31 inches