The Mythical Man-Month: Essays on Software Engineering is a book on software engineering and project management by Fred Brooks first published in 1975, with subsequent editions in 1982 and 1995. Its central theme is that adding manpower to a software project that is behind schedule delays it even longer. This idea is known as Brooks's law, and is presented along with the second-system effect and advocacy of prototyping.

Frederick Phillips Brooks Jr. was an American computer architect, software engineer, and computer scientist, best known for managing the development of IBM's System/360 family of computers and the OS/360 software support package, then later writing candidly about those experiences in his seminal book The Mythical Man-Month.