When Marcel Duchamp invented the readymade 100 years ago, it was not foreseeable that arbitrary everyday objects would have such a lasting impact on art. The book "The Readymade Century" sheds light on his readymades from two perspectives: The Readymade Index examines the genesis and consistency of Duchamp's concept during the first fifty years of the Readymade Century, from 1914 to 1964. The second part, Readymade Exposition, describes the far-reaching impact that extends well beyond the artist's lifetime. The hinge between the two chapters is formed by the edition of Duchamp's readymades as multiples and the exhibition of Andy Warhol's Brillo Boxes. Concurrently, yet independently, these two events in 1964 mark a turning point in the middle of the Readymade Century, which has immediate relevance for today's artistic practices of the "already made.".