Susan Coolidge was the pen name of Sarah Chauncey Woolsey, a distinguished American writer of children's books. She was born on January 29, 1835, in Cleveland, Ohio, into the affluent and influential Dwight Family of New England. Her father, John Mumford Woolsey, and mother, Jane Andrews, were both significant figures during their time. Coolidge had a notable connection as her niece was the author and poet, Gamel Woolsey.
Coolidge spent most of her childhood in New Haven, Connecticut, after her family moved there in 1852. She served as a nurse during the American Civil War, and it was after the war that she began her writing career. Coolidge never married and resided in her family home in Newport, Rhode Island, until her death. Throughout her life, she also undertook editorial work, credited for editing The Diary and Letters of France Burney and The Autobiography & correspondence of Mrs. Delaney.
As a writer, Coolidge is best known for her classic children's novel, What Katy Did (1872). The Carr family in the novel was modeled after her own, with Katy Carr inspired by Susan (Sarah) herself. The novel's brothers and sisters were modeled on Coolidge's four younger Woolsey siblings. The series, known as the Katy Did series, became highly popular and remains a classic in children's literature to this day.