She and Edgar Allan Woolf worked as a screenwriting team in Hollywood during the 1930s; they wrote scripts for ten films during that decade. They were called in to re-write Noel Langley's script for the Oz film in the summer of 1938; some of their changes were preserved in the final version of the movie — most notably, perhaps, their "There's no place like home" ending. The idea of multiple roles for the actor playing the Wizard was also a Ryerson/Woolf inspiration. They created Professor Marvel as the Kansas equivalent of the Wizard, and named the good witch of the north Glinda.
One peculiarity of the Ryerson/Woolf screenplay was that no one died in it — not even the Wicked Witch of the East. The writers considered death inappropriate in a movie for children.
Both the Langley and Ryerson/Woolf scripts added new characters and subplots and other extraneous matter to the story — which was weeded out of the final version of the script as prepared by John Lee Mahin.
Ryerson married writer Colin Clements, and collaborated with him on stage plays. She also wrote plays and other works on her own.