I bought the 1-2 yr old size for my one year old- but it was way too long! So I actually flip flopped my daughters outfits and put this on my three year old and it fit perfectly. So something to keep in mind- go small when ordering. I also had to snip the neck to get it over my daughters head (which is on the small side). Other than that the costume is super cute and was a big hit at the party.