I'm 5'2", 140 lb, so I should fit either size, but I bought the medium/large to make sure I'd have lots of room to move around in them, and they're STILL freakishly small. Oddly enough, the length is the problem -- I'm quite short with short legs, yet it's very hard to stretch them all the way up my legs, and they tend to slip down while I'm wearing them.

It's a pity, because they're soooooo cozy. The fleece inside is amazing.