After winning the part of Pookie Adams, Liza Minnelli had a copy of the script sent over to her mother, Judy Garland, who read it and thought the part of this troubled, friendless girl would be an unattractive role for her daughter. Minnelli says she became defensive and argued that Pookie was a great role for any actress, but that Garland was personally concerned Minnelli identified too closely with Pookie.
Alan J. Pakula recalled that Liza Minnelli became very attached to him as a father-figure on the set, always asking Pakula to tell her the story's plot in child-like terms before a big scene was to be shot. He also said that Liza carried around the book by John Nichols "like a Bible" until she knew the character of Pookie Adams inside and out.
Liza Minnelli's big telephone scene--where Pookie asks Jerry if she can spend her vacation with him at his dorm--was the first scene to be shot. Parts of this dramatic sequence were later used in the trailer, but with a different actor voicing Jerry.
Uncredited grip Martin Kashuk designed the $50,000 "minicrane," which was used during the six weeks of location shooting in New York. The crane had the capacity to raise the camera twenty feet into the air, and was attached to an Austin, which could move at speeds up to sixty miles per hour and had "self-levelling equipment" that facilitated moving shots on uneven roads without the need for track to be laid.
According to a Variety article in March 2021, Liza Minnelli read the book and said to her father, director Vincente Minnelli, "Daddy, if they ever make anything out of this, I want to play the girl Pookie Adams." When Vincente's friend director Alan Pakula announced he was making it, Vincente told him Liza wanted to play Pookie when Pakula came over to their house. Liza quickly told him she'd audition for it. Pakula let her and ended up giving her the role.