Hi Dawn,

Regardless of size, can he comfortably wear it now? Did he carry a load in it around the store? Was the pack he tried on at least an Osprey, if not an Exos 58? All three considerations are going to be the best way to assess the here and now. As for growth- I have a 13 year old son. Over the course of the last two years, he was in between a youth fit and a small men's size. We ended up settling on a women's Kelty to get him the proper fit. He's simply exploded in height and torso size in just the last six months or so. I just fitted and purchased a new Osprey Aether 70 pack for him that's a men's large, and the fit was suddenly perfect. Scary stuff in terms of my gear and food budget, but again, the point is, as long as your son can wear it now, it never hurts to plan for the inevitable, and with that overlap in torso measurements, the medium would be the way to go IMO. Hope that helps.

** I wanted to add- this pack will definitely last over two years, and Osprey has one of the best warranties in the business to back it, but, if he's going to be looking at week long trips in a couple years, even though 58L is going to be perfect now, it will also be pushing it on the volume he'll need to carry all his gear for trips of that duration. Scouts are about being prepared, not necessarily as being minimalists. Ask some of the older scouts about their gear lists before you absolutely commit.

Thank you guys so much I know on here they do not have teh torso size for this but on Zappos they list this as being for a 18-20 inch torso.