I'm 5' tall and 95 pounds and ordered this in an xxsp.  it's a little loose but still looks really attractive on my body.  it's warmer and thicker than i thought it would be and lined.  i love it!  taller petites might want to size into regular because even on my super-petite body it hit a few inches above the knees - perfect length for me but will hit higher for those taller.
it's going to become a staple!