My son just turned 5 in oct. 2012. He is average size 42 lbs slim. The suit was a little snug in the butt, the muscle torso fit like a glove, but a little snug, he was unable to wear a under shirt or the 3 Velcro buttons wouldn't close. All in all the suit was well made(except for the closure in back ). The glow in the dark front never glowed.