These pants are 100% true to size (whatever that means anymore...i'm a 26 in paige and ag.  i'm 5''6, weigh around 115, have long legs and i ordered the 0p.  the zero petite are still a little long, with a slight heel they're perfect.  they don't have stretch in them, but do to the fit and fabric...the material does expand, because they're thin and breezy.  i absolutely love them.  can't wait to order other colors of the same style.  these are my new favorite pants.