I bought these for my 10 month old who is very tall for her size so I ordered the 18-24 month size.  They worked perfectly.  They are great quality- they wash well, look great and feel comfy.  They are almost like a hybrid between leggings and tights.  The thickness of them was perfect to pair with her Christmas dress and I felt better about her wearing these than thin tights that would have left her little legs cold in this Midwest winter weather.  I will definitely buy these again in other colors, they are just so cute and she seemed very content wearing them.