Sarah Chauncey Woolsey (January 29, 1835 – April 9, 1905) was an American children's author who wrote under the pen name Susan Coolidg . Woolsey was born into the wealthy, influential New England Dwight family, in Cleveland, Ohio. Woolsey worked as a nurse during the American Civil War (1861–1865), after which she started to write. She is best known for her classic children's novel What Katy Did (1872). The fictional Carr family was modeled after her own, with Katy Carr inspired by Woolsey herself.
«What Katy Did» follows 12-year-old Katy Carr. She lives with her widowed father and her two brothers and three sisters in Burnet, a small midwestern town. Bright, headstrong Katy can hardly avoid getting into mischief almost daily. When her mother died four years earlier, Katy promised to be a little mother to her siblings, but mainly she is the kind of big sister who is sometimes impatient or cross with them, but leads them into all sorts of exciting adventures.