For reference, I am 5'6" and 124# and ordered a medium in this pant.  However, I did not keep the pant because the leg opening is very wide at 16" which made the pant look like a stovepit fit - not at all flattering.  The Zappo's site stated that the leg opening was 12".  I don't know if there are different versions of this pant but something to keep in mind if you don't like a baggy leg opening.  The fabric was nice and the medium fit perfectly but the wide leg opening was not reflected in the photo.