RUNS SMALL....just like all the previous reviews read.  I purchased a 2T for my daughter to wear this Halloween.  She is in 18 mon clothing (she will be 16 mon when she wears this.)  I tried it on her and def runs small.  The only part I feels runs true to size was the arm length.  The arms gather so the length is not an issue.
There was a small tear in the front of the plaid shirt.  Not large enough to return since she will only wear this once (but you can see it!).  Hat fits fine and show covers will fit as long as they do not go over a very thick bulky shoe.