I ordered this for my son who is 9, wears a size 10, and is somewhat tall for his age.  The costume was great except that it was a little too short.  It worked fine, but I would have liked it about 3-4 inches longer.  It's pretty lightweight and you can see dark clothing through it.  If I'd been planning ahead I would have bought a white turtleneck to wear under it so his neck wouldn't be visible.