In 1939, Major Armstrong turned his attentions towards commercial broadcasting. This spurred the CURC to shift from a club concerned with radio technology to a de facto radio station that provided broadcasts to the campus. It was in these early days of radio that the FCC granted the station its license, on October 10, 1941.
For the next ten to twenty years, WKCR-FM functioned as an intellectual radio station. Programming was largely Columbia classroom events, classical music, and broadcasts from the United Nations. After the student uprising of 1968, this format changed. The station shifted its emphasis from being an illustration of the university to presenting commercially inviable programming to the New York metropolitan area. Jazz became the core of this broadcast approach, which is neatly summarized in the slogan, "The Alternative." The descriptions of individual departments contain information about WKCR's concept of alternative programming.
In the late 70s, under the direction of Tim Page, the station presented the radio premieres of several leading minimalist compositions, including Philip Glass's "Einstein on the Beach" and Steve Reich's "Music for 18 Musicians." It was the first station in the country to pay attention to this important and eventually very popular form of avant-garde music. Page also produced a benefit concert for the station at Carnegie Hall, with appearances by Reich, Glass, John Cale and David Bowie, among many others.
In 1977, the station became the first radio (or television) station to transmit from the antenna atop the World Trade Center, having previously broadcast from an antenna atop the DuMont Building, a 42-story structure at 515 Madison Avenue.