A sustaining program is a radio or television program that, despite airing on a commercial broadcast station, does not have commercial sponsorship or advertising. This term, mostly used in the United States, was common in the early days of radio, but has become unfamiliar, due to the nearly universal use of commercial advertising on radio and television.
Commercial radio stations began broadcasting in the early 1920s, but it would be over a decade before the concept of selling over-the-air advertising would catch on. Many radio stations were established by radio equipment manufacturers and retailers such as RCA and programming was provided to sell the still-patented radio transmitters and receivers (thus effectively establishing a one-time fee model). Programming was financed from the sale of the equipment. Other radio stations and programs were provided as a public service through endowments or municipal financing; a few were operated by universities or public institutions for educational purposes. Some early radio stations were owned and operated by newspaper publishers. Radio gave an added forum to express the opinions of the owners and resulted in increased newspaper sales.
In effect, most early radio stations had only one sponsor, the company that owned the station. Before long, these companies began to provide their programs to independently owned radio stations, creating the first radio networks.
The radio station owners soon realized they could earn more money by selling sponsorship rights to other businesses, especially as the patents expired and most people already owned a radio. By the 1930s, it was common practice for programs to be owned and produced by the advertiser, who in turn leased production facilities and air time from the network. The advertiser frequently got top billing over the star, as in The Pepsodent Show starring Bob Hope or The Chase and Sanborn Hour starring Edgar Bergen and Charlie McCarthy. If a sponsor dropped an otherwise popular show, the network might choose to continue producing the show itself while it sought a new producer/sponsor, and in the meantime sell individual commercial slots in the show to any sponsors interested. When this happened, the network was "sustaining" the show until a new permanent sponsor took over production.
In the early days of radio broadcasting, sustaining programming included a wide variety of shows offered by radio stations and networks to attract audiences to the new medium. New programs would often go on the air on a sustaining basis in the hopes of attracting a sponsor. If a radio station and its shows became popular, then it was more likely to attract sponsors.