Born in Stockbridge, Massachusetts, she was the daughter of a prosperous lawyer and successful politician, Theodore Sedgwick, who later became a judge of the Massachusetts Supreme Judicial Court and Speaker of the United States House of Representatives. She was sent to study at a finishing school in Boston, and as a young woman she took charge of a school in Lenox. Sedgwick's conversion from Calvinism to Unitarianism led her to write a pamphlet denouncing religious intolerance that evolved into her first novel, A New-England Tale.
Much in demand, from the 1820s to the 1850s Catharine Sedgwick made a good living writing short stories for a variety of periodicals. Following her death in 1867, by the end of the 19th century she had been relegated to near obscurity. Interest in her works and an appreciation of her contribution to American literature was largely stimulated by the advent of low-cost electronic reproductions that became available at the end of the 20th century.
Edgar Allan Poe gave a description of her in his The Literati of New York City
She is about the medium height, perhaps a little below it. Her forehead is an unusually fine one nose of a slightly Roman curve; eyes dark and piercing; mouth well-formed and remarkably pleasant in its expression. The portrait in “Graham's Magazine” is by no means a likeness, and, although the hair is represented as curled, (Miss Sedgwick at present wears a cap...at least, most usually,) gives her the air of being much older than she is.
She is buried in the family plot in Stockbridge, Massachusetts.
In 1827 her third novel Hope Leslie recounted a dramatic conflict between the British Empire, colonists and Native Americans. The book earned a large readership and established her reputation in both the United States and Great Britain, making her one of the most talked-about female novelists of her time. Sedgwick's writings involved American settings, combining patriotism with protestations against Puritan oppressiveness. Her topics would become important to the creation of a national literature enhanced through her detailed descriptions of nature. Sedgwick created spirited heroines who, as the focal point of her stories, did not conform to the stereotypical conduct of women at the time. In her later work, Married or Single, she put forth the bold idea that women should not marry if it meant they would lose their self-respect.
Sedgwick's novel The Linwoods; or, 'Sixty Years Since' in America (1835) is a historical romance set during the American Revolution. Sedgwick uses a cosmopolitan framework to shed light on American character and national identity in the early republic through America's relationship with Britain and France. The delicate balance between American nationalism and cosmopolitanism is idealized in the novel through the character of the Marquis de Lafayette, as is the struggle between Old World notions of class and American democracy.
Sedgwick's novel Live and Let Live; or, Domestic Service Illustrated (1837) depicts the ideal workplaces for working-class women to develop domestic skills. Sedgwick's demonstration of the best relationship between mistress-employer and housekeepers reflects a return to aristocratic class relations that includes employer respect for the employee's humanity and political rights. Domestic economist Catharine Beecher's subsequent publications, 'A Treatise on Domestic Economy' (1841) and 'The American Woman's Home' (1869), followed up on Sedgwick's novel to similarly promote the importance of the labor contract in these relationships.
Using the techniques of the 'New Criticism' of the 1950s, Fetterley (1998) provides a close reading of Sedgwick's novel Hope Leslie (1827) that reveals both the areas in which the heroine Leslie, and thus the author Sedgwick, is ahead of her time, and the areas in which she is a product of her time. In the novel, Leslie is constantly challenging the role of women set out during the colonial period. Sedgwick portrays Leslie as living in a hostile world, where she, as a woman, invents a holistic public role for herself that is not separate from the private sphere. Sedgwick constantly uses the rhetoric of "sameness" when comparing Leslie and the main male character, Everell. However, at the same time that Hope Leslie is radical, it is SOME ways conservative as well. When reunited with her long-lost sister who has taken on an Indian identity, Leslie is repulsed by the fact that she has "gone native." Sedgwick portrays the Indian woman Magawisca in a sympathetic light, but viewed nonwhite women as a threat to the efforts of white women to establish themselves, and thus chose to write nonwhite women out of the future by acknowledging the contemporary conservative belief that American Indians were a vanishing race.