"Saturday in the Park" was very successful upon release, reaching #3 on the Billboard Hot 100, becoming the band's highest-charting single to date, helping lift the album to #1.Billboard ranked it as the No. 76 song for 1972. The single was certified Gold by the RIAA, selling over 1,000,000 units in the US alone.

According to fellow Chicago member Walter Parazaider, Lamm was inspired to write the song during the recording of V in New York City on July 4, 1971 (actually a Sunday):

Robert came back to the hotel from Central Park very excited after seeing the steel drum players, singers, dancers, and jugglers. I said, 'Man, it's time to put music to this!

The line "singing Italian songs" is followed by "Eh Cumpari" and then Italian-sounding nonsense words, in the studio version of the song, rendered in the printed lyrics as "?". Piano, guitar, and vocal sheet music arrangements have often read "improvised Italian lyrics" in parentheses after this line. However, in a film of Chicago performing "Saturday in the Park", at the Arie Crown Theater in Chicago, in 1972, Robert Lamm clearly sings, "Eh Cumpari, ci vo sunari," the first line of a song known as "Eh, Cumpari!", which was made famous by Julius La Rosa in 1953.

"Saturday in the Park" has been used in a popular commercial in Japan, advertising a marketing campaign known as "Parkhouse".

The song is played at Saturday afternoon baseball games at Wrigley Field in Chicago (as Terry Kath grew up on the North Side of Chicago), Nationals Park in Washington, Oriole Park at Camden Yards in Baltimore, Yankee Stadium and Citi Field in New York, and Coors Field in Denver.

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Wikipedia