Joseph Cornell and Marcel Duchamp met for the first time in 1933 in New York. It was the start of an artistic cooperation and friendship between two of the 20th century's most innovative artists - a relationship that has never before been documented. Cornell supported Duchamp in creating his "portable museum", the "box in a valise". This rapidly led the two artists to discover their common interest in curious objects: optical devices, broken glass and all kinds of objets trouvés. At the heart of this book is Joseph Carroll's "Duchamp Dossier" (ca. 1934-1953), which was first discovered after Duchamp's death in 1968 and is still unknown to the wider public today. The dossier contains 117 small objects, documents and photographs reproduced in color on double- sided pages on a scale of 2:3. The objects - "trash", souvenirs and letters - are documented and analysed in a detailed text with lavish illustrations. The book also presents other works by Cornell and Duchamp that vividly demonstrate the affinity between the two artists. The artists: Marcel Duchamp (Blainville near Rouen 1887-1968 Neuilly-sur- Seine). 1904 studied at the Académie Julian in Paris. 1913 exhibited "Nude descending a staircase" at the Armory Show in New York. He created the first ready-made in 1914. From 1915 he stayed alternately in Paris and New York. After 1923 Duchamp was no longer active as an artist apart from collaboration on some experimental films. Joseph Cornell (Nyack/N.Y. 1903-1972 New York). 1917-1921 attended Phillips Academy in Andover, Massachusetts. In 1930 Cornell made his first poetic collages and from 1933 he built his famous object boxes with objets trouvés.