The family Chinchillidae is in the order Rodentia and consists of the chinchillas, the viscachas, and their fossil relatives. This family is restricted to southern and western South America, mostly living in mountainous regions of the Andes but one species living on plains. They are medium to large-sized rodents, weighing from 800 g (28 oz) to 8 kg (18 lb), with strong hind legs and large ears and a bushy tail. All species have thick, soft fur, which is considered valuable in some cultures.

Chinchillas are either of two species of crepuscular rodents of the parvorder Caviomorpha, and are native to the Andes mountains in South America. They live in colonies called "herds" at high elevations up to 4,270 m (14,000 ft). Historically, chinchillas lived in an area that included parts of Bolivia, Peru and Chile, but today, colonies in the wild are known only in Chile. Along with their relatives, viscachas, they make up the family Chinchillidae. They are also related to the chinchilla rat.