Fashion is a subject that has long been marginalized in art history and in museums. And yet, one of the most well-known artists in the twentieth century - Marcel Duchamp - created works that challenge the notion that fashion does not belong in the museum. As well, there is material evidence of his engagement with clothing as part of his oeuvre. This book reveals that clothing and dressing are significant themes that recur in Duchamp's life and his work - including his drawings, his fashioning of his body, his readymades, and in his curatorial gestures. In examining the items of clothing worn by Duchamp and the related traces of his wardrobe management, Duchamp is unmasked as a dandy. His waistcoat readymade series 'Made to Measure' (1957-1961) is in fact a remarkable and deliberate effort to recalibrate the definition of the readymade to include clothing. With this little-studied readymade series, Duchamp established a precedent for sartorial art as a valid form of artistic expression. In considering the material traces of Duchamp's fashioning of his body and identity in his work and life, this book makes a highly original contribution to the understanding of Duchamp's work as well as the significance of the clothed body in the vanguard of Modernism. Ultimately, this book explains the relevance of fashion in the museum to modern audiences today.