If you happen to be a woman who is lucky enough to have tiny, meatless legs, then don't worry about ordering up. If you do have a little meat, order up. There is hardly any stretch to the jeans. They're only 2% spandex. Normally, I'm a size 2, but I listened to advise thankfully, and ordered the 5. They are snug in the leg, and I still have to wear a belt, because the waist is a bit roomy. I'm not a girl without hips, either. So, model tall and skinny? They'll fit awesome! Everyone else, for sure size up.