[2] While in college, he supported himself by playing the violin and saxophone at weddings and bar mitzvahs; and later, realizing that he was not a very good musician, by organizing dance bands for the same events.

[1] He then went to the University of Vienna to study for a year and upon returning to Chicago, he was appointed chief resident at Cook County Hospital.

[1] Stein continued to book bands on the side and eventually left his secure life as an ophthalmologist for the entertainment industry.

At the time, Chicago was a major centre for jazz—which had displaced ragtime as the popular music—and when combined with Prohibition, created a lucrative environment for entertainment.

Spreading from the one-man start to bases in New York, Los Angeles, Dallas and Cleveland, Stein's organization by the mid-1930s represented more than half of the nation's major bands, including those of Ted Weems, Isham Jones and Benny Goodman.

[2] In 1937, MCA opened an agency in Hollywood and began to represent such stars as Bette Davis, Betty Grable, Joan Crawford, Greta Garbo, Eddie Cantor, Ingrid Bergman, Frank Sinatra and Jack Benny.

In 1958, it acquired the 430-acre (1.7 km2) Universal Studios moving into producing television programs and motion pictures while still representing talent clients, resulting in accusations of conflict of interest.

Dr. Stein's biggest accomplishment came in 1962 when his company announced it was buying American Decca Records and its subsidiary Universal Pictures; however that same year, a federal antitrust suit was started against MCA.