What Katy Did is a children's book written by Sarah Chauncey Woolsey under her pen name Susan Coolidge.
It follows the adventures of a twelve-year-old American girl, Katy Carr, and her family who live in the fictional lakeside Ohio town of Burnet in the 1860s. Katy is a tall untidy tomboy, forever getting into scrapes but wishing to be beautiful and beloved. When a terrible accident makes her an invalid, her illness and four-year recovery gradually teach her to be as good and kind as she has always wanted. Two sequels follow Katy as she grows up: What Katy Did at School and What Katy Did Next.
Two further sequels relating the adventures of Katy's younger siblings were also published—Clover and In the High Valley. The books were frequently reprinted and all are available online. Coolidge modeled Katy on her own childhood self, and the other 'Little Carrs' on her brothers and sisters. The title is a play on the katydid, a family of insects – which explains the insects on the first edition book cover. 12-year-old Katy Carr lives with her widowed father and her two brothers and three sisters in Burnet, a small midwestern town. Her father is a very busy doctor who works long hours; the children are mostly in the care of his sister Aunt Izzie, who is very particular and something of a scold. Bright, headstrong Katy can hardly avoid getting into mischief almost daily under these circumstances, but she is unfailingly remorseful afterward.
She dreams of someday doing something "grand" with her life: painting famous pictures, saving the lives of drowning people, or leading a crusade on a white horse. She also wants to be "beautiful, of course, and good if I can." 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.