Peter Cetera was in the band Chicago.
Peter Cetera . His career as a recording artist encompasses seventeen albums with Chicago and eight solo albums . With `` If You Leave Me Now , '' a song written and sung by Cetera on the group 's tenth album , Chicago garnered its first Grammy Award . In 2014 , the first album by the group Chicago , Chicago Transit Authority ( Columbia , 1969 ) , with Cetera on bass and vocals , was inducted into the Grammy Hall of Fame . Cetera was inducted into the Rock and Roll Hall of Fame as a member of Chicago in April 2016 , and Cetera , Robert Lamm , and James Pankow are among the 2017 Songwriters Hall of Fame inductees for their songwriting efforts as members of the group .