In January 1970, WKDA-FM began playing album-oriented rock, aimed especially at Nashville's large college student population, first at night only, and, then, beginning in March concurrent with a format change of the AM to country, full-time, for about a year and a half. Afterward, in the daytime, the station employed a mix of rock and Top 40 music, while switching to hard and progressive rock at night, during most of the 1970s and early 1980s. As the FM format grew, it soon became the dominant station of the two, which eventually separated. For some years from the late 1970s and into late 1980s, "KDF" (as it was popularly known after its call sign officially changed to WKDF in late 1976) was the dominant station in the Nashville market as determined by the number of listeners reported by Arbitron, again thanks to its vast popularity among younger listeners. Although WKDF was challenged by competitor stations in the late 1980s into the mid-1990s, it continued to place first, second, or third with Arbitron during this period. After a short stint with a hard rock format from 1992 to 1993, WKDF's format shifted to an active rock format in 1993, then alternative rock in 1996. In July 1997 the format was changed again, to adult album alternative, which led to a precipitous fall in ratings from third in the market to 13th.