My daughter is not quite 2 years old and wears 18-24 month clothing, sometimes 2T in shirts so that they are long enough.  I ordered this outfit in a 24mo/ 2T thinking I'd be safe on size, but it just barely fit.  It was a bit of a stretch to get it pulled over her shoulders and velcroed on the back.  I had hoped to put clothing under it to keep her warm while trick or treating, but it was way too small to do so.  For anyone ordering in the future that lives in a cooler climate: the material is a little thin, so I would recommend clothing underneath.  There is a fairly long open slit in the back that will be chilly without a shirt under or coat over it.  All that being said, the outfit was absolutely adorable and received MANY compliments.  Great feature that the tail velcroes on and off for riding in the carseat, etc.  Fair warning that the fur edging is like a feather boa and sheds quite a bit.