The callsign is a reference to "The Soy City," a nickname for Decatur, Illinois, where the major industry is soybean processing.
The station has operated as "Y103" with a Top 40 format since 1980. Initially the station was programmed with a syndicated Top 40 package from Peters Productions known as "The Love Rock," which continued for some time into the 1980s. The station has been operating mostly live and local since 2000, though they do air Ryan Seacrest from Premiere Radio Networks weekdays 3-6pm. Prior to "Y103" and back to its sign-on in the 1960s, WSOY-FM had been a simulcast of WSOY-AM, then automated country, then "Music Just for the Two of Us" (automated easy listening).