On September 16, 1940, the station signed on under the WLAV call sign (which stood for Leonard Adrian Versluis, the station's original owner). It added WLAV-FM in 1947. WLAV became a full-time Top 40 music station in the summer of 1963, and was originally consulted by Mike Joseph, who later went on to develop the Hot Hits format in the late 1970s. One popular WLAV personality was Larry Adderley, who would later work as a sportscaster at various radio and TV stations in the Detroit media market as well as an announcer for the Detroit Tigers.