Super soft cotton, very smooth & comfy elastic-I always wear Gap cotton bikinis & these just might be my new favorites-the elastics are even finer & more comfortable-and the price is great! I just wish they would come in the solid colors of your choice-not just the assorted available. A lot of reviews said order up a size-I usually wear a size Large in Gap and the size 8s in Vanity Fair were perfect.  They shipped super fast, too!  All around excellent and I would definitely recommend!