The papers of art collector Emily Hall Tremaine measure 8.9 linear feet and date from 1890 to 2000. Found within the papers are biographical materials on the Hall, von Romberg, and Tremaine families, including a sound cassette on the Tremaines; personal correspondence; art collection files, which include inventory binders, records of sales and donations, artist files, exhibition loan files, and reproduction request files; 2 scrapbooks documenting Tremaine's first marriage to Baron Maximilian von Romberg; and photographs of Tremaine, her family and friends, and works of art from her collection. There are also materials related the 1984 exhibition The Tremaine collection: 20th Century Masters at the Wadsworth Athenaeum, including a video recording of Philip Johnson's exhibition lecture.

The collection documents the technology of lighting and various business aspects of the General Electric Lighting Division throughout the 20th century and consists of correspondence, bulletins, price lists, business record books, stock certificates, sales and advertising materials, scrapbooks, photographs, and lantern slides.

The Leo Castelli Gallery records measure 215.9 linear feet and date from circa 1880-2000, with the bulk of the materials dating from the gallery's founding in 1957 through Leo Castelli's death in 1999. The major influence of dealer Leo Castelli and his gallery on the development of mid-to-late twentieth century modern art in America is well-documented through business and scattered personal correspondence, administrative files, exhibition files, extensive artists' files and printed materials, posters, awards and recognitions, photographs, and sound and video recordings. Also included are records for the subsidiary firms of Castelli Graphics and Castelli/Sonnabend Tapes and Films.

The papers of painter and illustrator W. Langdon Kihn measure approximately 8.5 linear feet and date from 1904-1990, with the bulk of the materials dating from 1904-1957. Papers document Kihn's career and travels associated with his interests in documenting the native American tribal nations of the United States and Canada in portraiture and writings. Found here are biographical materials, voluminous correspondence, memoirs and writings, one travel diary, printed material, financial records, three sketchbooks, sketches, and photographs.

The papers of art historian, curator, and professor Robert Rosenblum measure 38.3 linear feet and 1.17 GB and date from circa 1927 to 2009, with the bulk dating from 1950 to 2006. They include biographical material, extensive personal and professional correspondence; lectures, writings, and writing project files by Rosenblum and others; exhibition files; research reference files; teaching files; personal business records; printed and digital material; photographs; and artwork.

The papers of art collectors, art patrons, and philanthropists Lawrence and Barbara Fleischman measure 4.9 linear feet and date from 1837 to 1984, with the bulk of the materials dating from 1935-1979. The papers are comprised mostly of correspondence with artists, museums, and arts organizations. Also found are scattered biographical materials, artists' autograph letters purchased by the Fleischmans, exhibition files, notes and writings, printed material, and photographs.

The papers of architectural historian, author, critic, teacher, and museum director, Henry-Russell Hitchcock, date from 1919-1987 and measure 24.8 linear feet. Almost all of the collection is comprised of Hitchcock's correspondence files relating to academic research, teaching, curatorial interests, and professional associations. Letters are from prominent architectural historians, architects, artists, preservationists, museum directors and curators, and family and friends. Also found are two feet of writings by Hitchcock and others, scattered biographical information, printed material, and photographs of Hitchcock and architecture.

The records of the Downtown Gallery date from 1824 to 1974 (bulk 1926-1969) and measure 109.56 linear feet. The records present a comprehensive portrait of a significant commercial gallery that operated as a successful business for more than forty years, representing major contemporary American artists and engendering appreciation for early American folk art. There is an unprocessed addition to this collection dating circa 1970 of a single financial/legal document.

The records of the Perls Galleries measure 79.6 linear feet and date from 1937 to 1997. Founded by Klaus Perls in 1937 and operating until 1997, the gallery dealt primarily in modern French art and the artwork of Alexander Calder. Found within the records are extensive correspondence (circa 44 linear feet) with artists, dealers, galleries, museums, and collectors; photographs and negatives of inventory and other artwork; exhibition files, scattered financial records; and exhibition catalogs and clippings.

The records of the American Federation of Arts (AFA) provide researchers with a complete set of documentation focusing on the founding and history of the organization from its inception through the 1960s. The collection measures 79.8 linear feet, and dates from 1895 through 1993, although the bulk of the material falls between 1909 and 1969. Valuable for its coverage of twentieth-century American art history, the collection also provides researchers with fairly comprehensive documentation of the many exhibitions and programs supported and implemented by the AFA to promote and study contemporary American art, both nationally and abroad.