Hans Richter was a central figure in the avant-garde for more than fifty years. Born in Berlin in 1888, he joined the Zurich Dada group in 1916, and within a few years was producing some of the first abstract films ever created. In the 1930s, he produced a surprising array of commercial and propaganda films for both communist and capitalist interests - a phase of his career that has been, until now, little examined. After moving to the United States in 1940, Richter taught at City College of New York, serving as both a mentor to numerous participants in the New American Cinema movement and a historiographer of Dada. Richter worked alongside or in direct collaboration with a virtual "Who's Who" of the avant-garde, including Hans Arp, Paul Bowles, John Cage, Alexander Calder, Jean Cocteau, Marcel Duchamp, Sergei Eisenstein, Max Ernst, Fernand Leger, El Lissitzky, Kasimir Malevich, Ludwig Mies van der Rohe, Kurt Schwitters, and Tristan Tzara. This book examines the ways in which these "encounters" - to use Richter's own term - with other artists engendered creativity, originality, and meaning throughout his career until his death in 1976. The catalogue also includes a chronology and the first complete Richter filmography in English. Illustrating his work alongside that of his colleagues, this volume represents an important contribution to our understanding of the relationships between modernism's most experimental artists, movements, and generations.