"Baby, What a Big Surprise" is a power ballad written by Peter Cetera for the group Chicago and recorded for their album Chicago XI (1977), with Cetera singing lead vocals. The first single released from that album, it reached #4 on the U.S. Billboard Hot 100 chart. Carl Wilson of The Beach Boys provided additional backing vocals on the recording while saxophonist Walt Parazaider plays flute on the distinctive flute introduction and trumpeter Lee Loughnane plays a piccolo trumpet.