I bought this for my son for Halloween.  He just turned 2 about 1.5 months ago, and is bordering between size 2T and 3T.  I decided to buy this a little big (rather than small), and I'm glad I did.  This is a size 3T-4T, and it just fits about right.  The ears are WAY too small, though.  I may have to buy a headband with ears instead.  The costume itself is really adorable, and he loves it - just go for a slightly bigger size and plan on buying separate ears.