In the pre-Columbian Americas, every day was Halloween -- a time to wear masks. Masks were worn by children, shamans, dancers and ballplayers and accompanied rulers to the grave. Masks were donned to help win battles, conceal identities and throw great parties -- all of which is documented in the exhibition "Faces of Eternity: Masks of the Pre-Columbian Americas," at the Americas Society, 680 Park Avenue, at 68th Street, through Dec. 15.
The little-known story of the role of masks in North, Central and South America before the arrival of Europeans is told with 83 masks and sculptures made between 1000 B.C. and the 16th century. Many of the fantasy face coverings -- which depict fierce beasts, eccentric gods and human skulls -- are exhibited for the first time. Most were worn for celebrations, performances and burial and transformation rites; others were fashioned into jewelry or plaques that were affixed to buildings. The sculptures of masked people and animals were made for temples and tombs.
"The art of mask-making remained profoundly expressive of societies throughout the Americas until the conquest," said N. C. Christopher Couch, an assistant professor in the art department at Smith College and the show's curator. "What seems remarkable is that this is the first exhibition on the subject covering pre-Columbian masks." The exhibition catalogue ($17.50) is also the first book on the subject.
The most exuberant object in the show is one of the smallest -- a three-inch-tall clay figure of a man grasping the flippers of a killer-whale mask that sits on his head, as if he were holding onto his hat in the wind. This comical sculpture, made between 200 B.C. and 400 A.D. and found in a tomb, is among the least threatening pieces on view.
Such helmet masks of West Mexico were often worn as part of costumes that covered the entire body; they transformed the wearers into whales, parrots, ducks or crabs. Mr. Couch said that such fantasy dress was probably used for centuries to establish hierarchy in Peru and Mexico before 500 A.D. Later, helmet masks were also worn by Aztec warriors and emperors.
Spectacular face coverings were a specialty of Peru. A craftsman of the Huari people devised a multicolored head of feathers with a bright blue nose, peach-colored cheeks and a black-and-white checkerboard mouth. One such piece on view was made between A.D. 600 and 1000 and was found with a mummy in a grave. Other Peruvian artisans of the same period shaped sheets of gold into human faces with tab-shaped ears and disk earrings.
Earlier Peruvian and Mexican masks, made between 200 B.C. and 400 A.D., are more expressive. A copper mask, with bulging white shell teeth and eyes, seethes with violence. A gold mask -- wild-eyed and grinning, with tears zigzagging down its cheeks -- is framed with appendages as if its hair were standing on end. Even more arresting is a round clay mask -- white on top, dark red below -- that suggests a conflict in people as old as man.
Among the show's surreal images is a compelling 2,000-year-old terra cotta tomb sculpture of a dachshund-like creature with the face of a man. It symbolizes the ancient Mexican belief that dogs accompanied the dead into the afterlife.
Perhaps the most haunting piece is a mosaic skull face from Puebla, Mexico, made between 1200 and 1500. Its eyes are sunken ovals, its mouth and chin are torn off, and its skin, of black stone speckled with turquoise, is peeling.
Under the Spanish, who disparaged masks as pagan images, these objects were banished from everyday life and reserved for theatrical use. Until recently, Mr. Couch said, most scholars did not realize their importance for state occasions in the highly sophisticated societies of Mexico and Peru. The Aztec emperor Mocteuczoma Xocoyotl (Montezuma) wore masks and presented a set of royal turquoise mosaic masks to the explorer Cortes on his arrival at Tenochtitlan in 1519.
"Faces of Eternity," financed in part by the National Endowment for the Arts and the New York State Council for the Arts, will travel to the North Carolina Museum of Art in Raleigh and the Museum of Fine Arts in Springfield, Mass.
It is one of at least six shows in New York this fall focusing on masks. "Modern Masks and Helmets" opened last month at the Museum of Modern Art. Also this fall are "Objects of Myth and Memory: American Indian Art at the Brooklyn Museum," through Dec. 29; "A Sacred Presence: Masks of Africa and the Himalayas" at Pace Primitive, 32 East 57th Street, through Nov. 30; "Chiefly Feasts: The Enduring Kwakiutl Potlatch" at the American Museum of Natural History, Oct. 18 to Feb. 3, and "Mask Images" at American Primitive Gallery, 596 Broadway, Oct. 29 to Nov. 30.
Photo: A mosaic skull mask from Mexico, made between 1200 and 1500 (Lynton Gardiner/Americas Society)