She is best known for writing The Kissing Hand, a picture book featuring anthropomorphic raccoons.
In 1980, after developing Juvenile Rheumatoid Arthritis, Penn was too ill to continue with ballet.
Due to many painful surgeries and not being able to walk for weeks led her to write more books like Blue Out of Season and No Bones About Driftiss.
Her best known book, The Kissing Hand, was a New York Times number one best seller and won the Distinguished Achievement Award for Excellence in Educational Journalism.
In 2004, A Pocket Full of Kisses also was a New York Times number one best seller.