Bought this jacket for my 5yr. old in Kindergarten. I purchased a small and the fit is perfect. It's a touch too big, which is exactly what I wanted, he has room to grow. I am not sure we'll utilize the "Room to Grow" feature, but it's nice to have. The 100g insulation is going to be perfect and will keep him warm during the Colorado winter. I purchased a snowboarding jacket, because they are normally a little tougher than a standard winter coat, this coat is no exception. Double taped seams, reinforced stitching and the shell looks tough enough to endure whatever my son puts it through. That coupled with its waterproof fabric and fixed hood make this jacket an awesome buy in my book. I would highly recommend this coat.