This is the first book to examine the key role played by New York gallerist and dealer Valentine Dudensing (1892-1967) in shaping the canon of modern art in the United States. It reveals how Dudensing developed relationships with the country’s leading art collectors, establishing the market and bringing some of modernism’s most celebrated artists to American consciousness in the process.Many of the paintings that he imported from Europe are now the cornerstones of US museum collections. Before the Museum of Modern Art opened in 1929, there were few places in New York to see contemporary art from Paris – the Valentine Gallery was one of them.In the intimate and elegant rooms of the gallery's townhouse premises on 57th Street, the public witnessed the first solo US shows of Giorgio de Chirico and Joan Miró, the first retrospective of Henri Matisse, and Piet Mondrian's only lifetime solo exhibition.In 1939, Pablo Picasso's masterpiece Guernica made its US debut there.Despite its preeminent reputation as a leading centre for modern art for over two decades, the Valentine Gallery name has been lost to history.Dudensing quietly closed the gallery in May 1947 and seemingly disappeared.His death two decades later went unreported in the press. Drawing on a wealth of primary source materials, including the gallery's long-lost sales records, The Valentine Gallery unearths the story of this preeminent forum for modern art, revealing how a pioneering gallerist brought the School of Paris to eminence in the US, and ultimately changed the country's artistic taste forever.