Chicago 18 is the fifteenth studio album by the American band Chicago, released on September 29, 1986. This album is the first without cofounding member Peter Cetera. This is also the first album to feature Jason Scheff on bass guitar and vocals. With Cetera having been fired by the band in 1985 because he wanted to record a solo album, Chicago eventually hired Scheff to fill Cetera's position as vocalist and bassist. With Scheff and Bill Champlin, who had joined the band in 1981, the most used voices in Chicago now belonged to its two newest recruits.