the most exclusive carnival balls required the use of the mask, and allowed the anonymity necessary for the daring playfulness expected at these events - for many years, these formal dances in rio were held at the teatro municipal, which also could includ costume contests. 

initially, these bailes had strict dress codes - men wore black tie apparel and women paraded around in expensive, detailed, and flamboyant costumes - with time these fashion trends changed.

in the 19th century, as well as the first half of the 20th century, costumes consisted of fuller outfits in the style of a grand baile - in the last seventy years, with carnival taking place at the hottest time of the year, the costumes worn to the balls have become considerably smaller and lighter in material.