Dresses are, like other outer clothing, above all worn with underwear. A wearer of a dress is likely to wear a conformation of panties http://www.onesmallchild.com/category/Communion%20Dresses/172/first-communion-dresses.htm as innerwear, though depending on the occasion, type of material, and type of skirt for modesty one may wear a bungle over the panties.