In late 1967, the station began programming progressive rock from 6pm to 6am. The programming proved successful enough to make the rock format full time by 1969, when Harden Broadcasting bought KNAC. Air talent at KNAC during this era included Jim Ladd (later of KLOS), Jerry Longden (later of KROQ) and Program Director Ron McCoy. Ladd left KNAC to work for KLOS in 1971, while McCoy stayed on through much of the 1970s. The station stayed with progressive rock until 1980, when it made a significant adjustment in its rock format.