Louise Hall was born in Oneonta, New York, to the family of a Congregationalist minister, and raised in Springfield, Massachusetts. She attended the Boston School of Fine Arts in 1917-1919, originally intending to become an illustrator. She decided she preferred history research, and went to work for the Girl Scouts of America. She first tried her skills at writing and editing with her work on the Girl Scout publication Trailmaker. In 1925, she married Cary Edwin Tharp, with whom she had two sons. Louise Hall Tharp published her first book, Tory Hole, in 1940. She went on to write a total of 17 historical novels for young people and historical biographies for older readers, and lectured widely. Her acclaimed 1965 biography of Isabella Stewart Gardener was a bestseller.