My 9 year old is a string bean and has this problem. I've had good luck with Hanna Andersson slim pants in the past.

Abercrombie makes size 9.

I will never understand why they do this in children's sizing. 9 year olds never have clothes that fit.

That's annoying. I'd skip the brand or hem the waist of the large. I'd rather get them shorts they can still fit in this fall.

My 9 yr old DS is in between a medium and a large in nike/under armour pants and shorts. Lengthwise large could work but the waist is huge. Anyone has any suggestions of different brands that might work or to just let him wear shorter pants/shorts..?