Her career in crossword puzzles began at the "New York World" in 1921. She had been hired as the secretary to the editor of the Sunday edition of the "New York World"; he eventually assigned her to assist crossword inventor Arthur Wynne, who was overloaded with reader submissions of puzzles – and with complaints about flawed puzzles. Petherbridge had never solved a puzzle herself and therefore chose puzzles to be printed without testing them, until fellow "World" employee Franklin Pierce Adams criticized her for it; in response, she tried the puzzles, and discovered to her dismay that some of them were unsolvable. She subsequently described her reaction as "(taking) an oath to edit the crosswords to the essence of perfection;" her puzzles eventually became more popular than Wynne's.