Night and Day (published on 20 October 1919) is a novel by Virginia Woolf. Set in Edwardian London, Night and Day contrasts the daily lives of two friends, Katharine Hilbery and Mary Datchet. The novel examines the relationships between love, marriage, happiness, and success.

Dialogue and descriptions of thought and actions are used in equal amount, unlike in Woolf's later book, To the Lighthouse. There are four major characters (Katharine Hilbery, Mary Datchet, Ralph Denham, and William Rodney) who are continually returned to. Night and Day deals with issues concerning women's suffrage, if love and marriage can coexist, and if marriage is necessary for happiness. Motifs throughout the book includes the stars and sky, the River Thames, and walks; also, Woolf makes many references to the works of William Shakespeare, especially from As You Like It.