Poor-fitting leggings or leggings made from low-quality, thin fabrics may tend to fall or roll down as you move. To find a pair of leggings that will stay put, make sure you're wearing the right size. Leggings should feel tight and lightly compressive against the skin, without digging into the waist or making it uncomfortable to freely move and breathe. Also, look for high-quality fabrics such as Nike Dri-FIT and a snug, comfortable waistband.