Mary Downing Hahn is an American writer celebrated for her young adult novels. She was born on December 9, 1937. Before embarking on her writing career, she worked as a school librarian.

Mary is renowned for her books such as Stepping On The Cracks and Wait Till Helen Comes. Since publishing her first book in 1979, she has written over 30 novels. Her latest novel, What We Saw, was published in September 2022.