These are great leggings. I'd personally never wear them alone, as the material is sturdy but because they're cotton, they are lighter than, say, a pair of Nike or Lululemon workout pants. I wear with mini-skirts (bodycon type). They aren't "thin" per se. If you're 20 and have a perfect body, sure, you could wear these alone. But you could wear anything! The waist band is more fitted than other leggings, but these fit me perfectly. At a size XL, they come to my belly button and I'm a 34" waist, 5'9", 180 pounds. They'll continue to fit even if I were 160 I'm sure. I wear a 33" inseam, and these are long, hooray! I'm sure they'd be long enough for those who wear a 34", even 35" inseam. They keep their shape - don't bag at the knee with wear. My last pair of American Apparel leggings lasted me about 5 years, wearing them a couple of times a month.