Founded in 1954, the museum collections have grown to 30,000 rare books, 300,000 manuscripts, 20,000 works of art on paper, 500 paintings, and 350 decorative art objects. The most notable donations are from poet Marianne Moore. She donated her literary papers, library, and furnishings from her living room in New York City. Long time trustee Maurice Sendak, author of, Where the Wild Things Are, has donated over 10,000 individual works and fifty plus books, which a selection is always on display in the Maurice Sendak Gallery.
The museum is the former home of Dr. A.S.W. Rosenbach and his brother and partner Philip. It is located at 2010 DeLancy Place and has recently expanded to 2008 DeLancy Place. From 1903 to 1953, the Rosenbach Company dealt rare books, manuscripts, and fine and decorative art. The company gave the brothers great wealth, which allowed the two brothers to keep many of their dealings for themselves.
Dr. Rosenbach was a big collector of rare books (his favorite being Don Quixote) and manuscripts, while his brother was a collector of eighteenth and nineteenth century French, English (mostly from royalty) and American furniture, glassware, silverware and sculptures from Egypt through the Renaissance.