Sarah Chauncey Woolsey (1835-1905) was an American children's author who wrote under the pen name Susan Coolidge. She was born in Cleveland, Ohio and spent much of her childhood in New Haven Connecticut. She worked as a nurse during the American Civil War (1861-1865), after which she started to write. Woolsey never married, and resided at her family home in Newport, R.I., until her death. She is best known for her classic children's novel What Katy Did (1872). The fictional Carr family was modelled after the author's own, with Katy Carr inspired by Susan (Sarah) herself, and the brothers and sisters modelled on Coolidge's Woolsey siblings. Two sequels follow Katy as she grows up: What Katy Did at School (1873) and What Katy Did Next (1886). Two further sequels were also published: Clover (1888) and In the High Valley (1890).