Mary Downing Hahn is an American writer of young adult novels and a former school librarian.
Born on December 9, 1937, she is widely known for her books such as Stepping On The Cracks and Wait Till Helen Comes.
She published her first book in 1979 and has since written over 30 novels. Her novel What We Saw was published in September 2022.

Mary grew up in a small shingled house at the end of Guilford Road in College Park, Maryland. Her childhood was filled with outdoor adventures and games with friends, which often inspired her storytelling.
She was known as the class artist in elementary school. Although she loved to read and draw, she struggled with writing reports due to the stringent requirements of outlines, perfect penmanship, and following directions.