"25 or 6 to 4" is a song written by Robert Lamm for the rock ban Chicago. It was recorded for their second album Chicago (1970) with Peter Cetera on lead vocals. The song was edited and released as a single in June of that year, climbing to number 4 on the U.S. Billboard Hot 100 chart and number seven on the UK Singles Chart. This recording features an electric guitar solo using a wah-wah pedal by Chicago guitarist Terry Kath, and has been included in numerous Chicago compilation albums.