This is a good costume.  My 2.5 y.o. wore it twice and it's held up.  I ordered the 3-4T size for him because I didn't want it to be tight.  It was perfect so I'd suggest sizing up.  He's a lean kid and on the tall side, but normally wouldn't fit into 4 T.  The design of the hood is great because it stays up and didn't seem to annoy him.