Florence Parry Heide was born in Pittsburgh and raised in Punxsutawney, Pennsylvania. She began her undergraduate studies at Wilson College in Chambersburg, Pennsylvania, then transferred to the University of California at Los Angeles, from which she received her degree in 1939. She moved to New York City and began working in advertising and public relations. When World War II began, she returned to Pittsburgh and became publicity director of The Pittsburgh Playhouse. She met her future husband in 1943 and married him six weeks later. After the war ended, Heide moved with her husband to Kenosha, Wisconsin, where her husband began a private law practice. She raised their children, and began writing children's books. In 1967, her first book, Maximilian, was published. Over the course of her career, she has published more than 100 books for children, including several collections of poetry.