L.F.
All of my kids are really skinny, and I've had good luck with Old Navy and Janie and Jack. Osh Kosh Genuine Kids (Target) also tends to run skinny, and they have a few pairs of jeans that have a knit waistband. My kids still can't button their pants, but for any pants with an adjustable waist, they are still able to just pull them on and off. Good luck!