If You Leave Me Now

Chicago was riding a string of album success in the mid-1970s when bass player Peter Cetera pulled out a song he had actually written years earlier, at the same time as "Wishing You Were Here" from Chicago VII. Composed on a guitar, "If You Leave Me Now" found Cetera pleading with a loved one not to walk away, asking how they could end it all that way. The band cut it for Chicago X, and Columbia Records released it as a single on July 30, 1976.

The recording came together quickly and largely live. Cetera sang while manager James William Guercio played acoustic guitar, Terry Kath took up bass, Robert Lamm played piano, and Danny Seraphine drummed. The band liked Guercio's demo guitar part so much they kept it, and Kath later overdubbed electric guitar. Cetera's vocal was redone afterward. Walter Parazaider later admitted he heard the finished song on the radio while cleaning his pool and mistook it for Paul McCartney.

The single became Chicago's first number one hit in the United States, topping the Billboard Hot 100 for two weeks beginning October 23, 1976, and it also reached the top in the UK, Australia, Ireland, Canada, and the Netherlands. It won the group its first Grammy Award, for Best Pop Vocal Performance by a Duo, Group or Chorus, with another going to arranger Jimmie Haskell and Guercio. By August 1978 it had sold 1.4 million copies in the United States alone.