My daughter wanted to be Ariel for Halloween this year, so i purchased this costume. I ordered the size small (4-6x) for my 4 year old daughter. I would say it is true to size.  It isn't even Halloween yet and she has wore it a couple of times and it has held up quite well. I sewed the shoulder pieces to the straps because the shoulder pieces wouldn't stay up on her. Also one of the ribbons on the dress ripped and couldn't be fixed. Other then that though the costume has held up quite well for the price. I would recommend it!!