Marcel Duchamp was one of the most enigmatic artists of the 20th century. In 1920 he invented an alter ego called Rrose S lavy, who would become one of the most dazzling characters in modern art. This ground-breaking book is the first to fully explore the complex history of Rrose S lavy in detail. It takes into account all the relevant works, reconstructs all the historical contexts, and sheds light on Duchamp's artistic attitude in the 1920s. "Known also under the name Rrose S lavy" (Duchamp), he playfully and ironically mocked the pretensions of the art and artists of his time, friends and foes alike. In Rrose S lavy, he, who rejected all -isms, took the liberty of creating his own -ism: a self-proclaimed "au-culism". Rrose S lavy was mocking art.