They have a flat front yoke and elastic in the back. The pattern is meant for slim sizes, so I didn't alter it at all, although they are still a little baggy.
The denim is super duper stretchy denim from fabric.com. I bought this for jeans for myself, but it's so stretchy I realized it could only be appropriate for denim leggings. My wardrobe simply doesn't have a place for denim leggings right now, so that yardage will turn into little girls' trousers.