The film was made and released about five years after its source play of the same name by Neil Simon was first performed in 1966. The original Broadway production of "Star Spangled Girl" opened at the Plymouth Theater on 21st December 1966 and ran for 261 performances until 5th August 1967. It starred Connie Stevens, Anthony Perkins and Richard Benjamin. The theater marquee for the production can be seen during the opening titles of TV series That Girl (1966). The play's setting is described in its intro as being "A duplex studio apartment in San Francisco".
This was the only ever Neil Simon written feature film directed by Jerry Paris though Paris did direct some episodes of Simon created TV series The Odd Couple (1970) and Barefoot in the Park (1970).
The film's source "Star Spangled Girl" play by Neil Simon was inspired by a lively argumentative political conversation that Simon overheard between an astronaut's conservative wife and liberal-minded writer Paddy Chayefsky.
The character that Amy Cooper sits next to on the Greyhound bus was made-up to resemble Joe Buck (played by Jon Voight) from the then recent film Midnight Cowboy (1969).