In the 20th century, the title and position typically brought with it an almost unlimited influence over the particular orchestra's affairs. As implied by the name, the music director not only conducts concerts, but also controls what music the orchestra will perform or record, and has much authority regarding hiring, firing, and other personnel decisions over an orchestra's musicians. Such authoritarian rule, once expected and even thought necessary for a symphonic ensemble to function properly, has loosened somewhat in the closing decades of the 20th century with the advent and encouragement of more power sharing and cooperative management styles (with the orchestra musicians themselves, the administrative staff, and volunteer board of directors). The music director in American lingo also assists with fund-raising, and also is the primary focus of publicity for the orchestra, as what is often called its "public face".
The term "music director" or "musical director" became common in the United States in the middle of the 20th century, following an evolution of titles. Early leaders of orchestras were simply designated as the "conductor." In the 1920s and 1930s, the term musical director began to be used, in order to delineate the fact that the person in this position was doing much more than just conducting, and to differentiate them from guest conductors who simply led one particular program or concert. George Szell, for instance, was appointed as "musical director" of the Cleveland Orchestra in 1946, and his position was so named until his death in 1970. His successor, Lorin Maazel, was given the title "music director." Other major American orchestras kept more current with the times and began using the simpler term in the 1950s and '60s.
Alternatively, the term "music director" used to appear in the film credits for a professional hired to supervise and direct the music selected for a film or music documentary, but today the more common designation is music supervisor.
The "music director" for a theatrical production or Broadway musical often serves as rehearsal pianist and conductor.
A music director of a radio station is responsible for interacting with record company representatives, auditioning new music, and making decisions (sometimes in conjunction with the program director) as to which songs get airplay, how much and when.
In India, where a large number of movies are produced as musicals, the term 'music director' is commonly used for the composer of the songs used in the film. Usually, another artist will receive the credit for the lyrics of the songs. In addition, the music director may also be involved in producing the songs for the film and for composing the score.