The station was founded as WPRU in 1940 by H. Grant Theis, a Princeton University student at the time. It often is cited as the oldest commercially licensed campus radio station in the United States. In 1955, WPRU got its FM license. It signed on as WPRB, the first college station on the FM dial in the United States, after the WPRU call sign was found to be already in use by a ship. It is considered a pioneer in FM Stereo broadcasting, transmitting a stereo signal beginning in 1964.