Max Wertheimer (1880-1943) was a German psychologist, philosopher and co-founder of Gestalt psychology. From 1912 to 1918 at the university in Frankfurt, he formulated the Gestalt theory with Wolfgang Köhler and Kurt Koffka. In 1933 Wertheimer emigrated to the United States, where he assumed a professorship at the New School for Social Research in New York City. He was also a guest lecturer at Princeton and Columbia universities. He wrote a number of essays and articles, and from 1921 to 1935 edited and published the multilanguage journal Psychologische Forschung. His only book-length work, Productiuve Thinking, was published posthumously in 1945. Collection consists of Max Wertheimer's professional and personal papers, as well as papers of his father, Wilhelm Wertheimer, and his colleague Erich Moritz von Hornbostel. Max Wertheimer papers include incoming letters, lectures, original typescript and related materials for his book, notes on experimental and social psychology, writings by other scholars with Wertheimer's annotations, sketches, and photographs. Wilhelm Wertheimer papers consist of correspondence, newsclippings and printed matter concerning his lectures on the warehouse question and sugar industry in Bohemia. Von Hornbostel papers include his correspondence with musicologists and ethnologists, manuscripts and copies of abstracts for scholarly articles, musical notes, and book reviews.