I did not have to size up or down because of my body type (broad padded back, wide rib cage, narrow hips, small bum.) however, it fits a little odd on me. the back darts that start at the waist and are supposed to curve for your behind settle too high and wrinkle. the waist is also too high. the shoulders are a bit tight. i am confused because i bought the exact same size pieced brocade (the colorful version of this dress) and that one actually fits spot on. i have a feeling if i go to the store