The American Curl is best known for its unique curled ears, which are the result of a spontaneous mutation. The ears are erect and open; curling away from the cat's face in a graceful arc as opposed to the Scottish Fold's which fold forward and downward. The ears give the breed an alert and happy appearance.

American Curl history began on a sunny day in June 1981 in Lakewood, California. A longhair silky black female kitten with unusual ears wandered up to the doorstep of Joe and Grace Ruga. Joe encouraged Grace not to feed the kitten, but Grace listening to her heart instead, left a bowl of food on the porch. The affectionate black kitten quickly worked her way into the Ruga's hearts and they named her Shulamith, which means "black but comely".

In December 1981, "Shulamith" delivered her first litter of four kittens. Of the four, two had ears that curled. A geneticist was contacted to study this phenomenon and he confirmed that this unusual ear was a genetic trait and was inherited in every case, causing it to be labelled a dominant gene, with no deformities attached to it. Referred to as a spontaneous mutation, the gene that causes the ear to curl appeared to be following a single dominant pattern.

Selective breeding and presentation of the Curls began in 1983 with American Curls officially accepted for CFA registration in 1986, and for championship competition in February 1993. American Curls were also the first breed to be admitted to the Championship Class as one breed with two coat lengths. Recognised as one of the United States native American breeds, the American Curl makes a wonderful pet and has remained very hearty with no genetic defects associated with the curl gene.

The ideal American Curl is a medium sized, alert cat with an elegant appearance and a sweet, open expression complimented by their remarkable ears. Due to their domestic ancestry, American Curls are available in both longhair and shorthair with both varieties having soft, silky, lustrous, flat-lying coats. The longhair Curl has the distinction of sporting a beautiful plumed tail. Because both coat lengths have minimal undercoat resulting in non-matting hair, grooming an American Curl is easy. An occasional bath and combing is all that is needed to keep the coat in good condition.

The most distinctive feature of the breed is their uniquely curled ears. The ears are quite firm to the touch, erect and open, curling up into a smooth arc. The American Curl ears have been compared to those of a Lynx with long tufts accentuating the swept back look complimenting the Curl's overall sophistication, stylish elegance, and alluring beauty. Care should be taken when handling the ears to avoid breaking the cartilage.

When Curls are born, their ears are straight, but within three to five days after birth, their ears begin to curl back. During the first 4 months, the kitten's ears will gradually curl and uncurl in varying degrees until they are set permanently at 4 months of age. It is usually around this time that the breeder can determine the quality of the cat based on the ear's degree of curl along with body type. First degree or almost straight is considered a pet, second degree or slightly curved is suitable for breeding, and third degree as show. Third degree is the most desirable curl to the ear, emulating the graceful curve of a full crescent.

In personality, American Curls are very people-oriented, faithful, and affectionate cats. Having an astute and curious temperament, they will readily assist their humans in whatever project is at hand and delight in "bumping heads" with their humans or new human acquaintances. American Curls love companionship and will adjust remarkably fast to other pet animals, children, and new situations. Curls are also even-tempered and intelligent, yet they retain their kitten-type behaviour throughout their adult life. First time admirers are always surprised by the American Curl's unique ears and impressed by their infectious personality, intelligence and beauty. Curls quickly endear themselves to their humans becoming a favourite with all who come to know them. Most American Curl owners enthusiastically acquire more than one Curl to share their home.

Besides being available in longhair and shorthair varieties, the American Curl can be any colour or coat pattern including the striking blue-eyed colourpoint. Eyes are also found in a rainbow of colours. The shorthaired variety is called the "Shorthair Curl" by some associations.