American Ballet Theatre
American Ballet Theatre (ABT), based in New York City, was one of the foremost ballet companies
Ballet company
A ballet company is a group of dancers who perform ballet, plus managerial and support staff. Most major ballet companies employ dancers on a year-round basis, except in the United States, where contracts for part of the year are the norm...

 of the 20th century. It continues as a leading dance company in the world today. A writer for London's The Observer
The Observer
The Observer is a British newspaper, published on Sundays. In the same place on the political spectrum as its daily sister paper The Guardian, which acquired it in 1993, it takes a liberal or social democratic line on most issues. It is the world's oldest Sunday newspaper.-Origins:The first issue,...

 describes the ABT along with the New York City Ballet
New York City Ballet
New York City Ballet is a ballet company founded in 1948 by choreographer George Balanchine and Lincoln Kirstein. Leon Barzin was the company's first music director. Balanchine and Jerome Robbins are considered the founding choreographers of the company...

 and the San Francisco Ballet
San Francisco Ballet
The San Francisco Ballet is a ballet company, founded in 1933 as the San Francisco Opera Ballet. The company is currently based in the War Memorial Opera House, San Francisco, under the direction of Helgi Tomasson. SFB is the first professional ballet company in the United States...

 to be a "triumvirate of great classical companies defining the American style on the world stage today".

There are three levels within the company (in ascending order): ABT's Corps de Ballet
Corps de ballet
In ballet, the corps de ballet is the group of dancers who are not soloists. They are a permanent part of the ballet company and often work as a backdrop for the principal dancers. A corps de ballet works as one, with synchronized movements and corresponding positioning on the stage...

, the soloists
Soloist (ballet)
In ballet, a soloist is a dancer in a ballet company above the corps de ballet but below principal dancer....

 and the principals
Principal dancer
A principal dancer is a dancer at the highest rank within a professional dance company, particularly a ballet company....

; there is also ABT II, formerly known as the ABT Studio Company.
The company was founded in 1937 as the Mordkin
Mikhail Mordkin
Mikhail Mordkin graduated from the Bolshoi Ballet School in 1899, and in the same year was appointed ballet master.He joined Diaghilev's ballet in 1909 as a leading dancer. After the first season he remained in Paris to dance with Pavlova...

, and then reorganized in 1940 with a new name as the Ballet Theatre.