Curator of graphic design and poster collections of the Museum of Modern Art, 1943-1970. After high school Constantine joined the College Art Association in 1930 as an editorial assistant on the journal Parnassus. She subsequently received a B.A. and M.A. from New York University. Later she attended the graduate school of the National Autonomous University of Mexico, Mexico City. Constantine joined the Committee Against War and Fascism and traveled to Mexico in 1936 where she discovered how Latin and Central American groups employed graphics to engage populist sentiment. In 1937 she joined the Office of the Coordinator of Inter-American Affairs, a United States government agency. There she met René d'Harnoncourt, later director at the Museum of Modern Art, New York. She organized a comprehensive Latin American poster collection displayed at the Library of Congress and today part of the Metropolitan Museum of Art's collection.She married Ralph Bettelheim (-1993), though she retained her maiden name professionally. She joined the Museum of Modern Art's architecture and design department in 1943 founded by Philip Johnson who returned to the department later and under whom she served. D'Harnoncourt, who assumed the directorship of MoMA in 1944, nutured Constantine's devotion to graphic arts. At MoMA, she mounted the museum's first exhibitions of art devoted to causes intended to spread awareness of specific social issues, including ''Polio Posters'' (1948). Constatinte raised objects of design art, which she called ''fugitive material,'' to a level of museum interest. The exhibitions, ''Olivetti: Design in Industry'' in 1952 was followed by ''signs in the Street'' in 1954 and ''Lettering by Hand'' in 1962. She mounted solo exhibitions for the commercial and graphic designers such as Alvin Lustig (1915-1955), Bruno Munari (1907-1998), Tadanori Yokoo (b. 1936) and Massimo Vignelli (b. 1931) and others. In 1968 she mounted exhibition, ''Word and Image,'' which showcased the Museum's major 20th-century posters collection. Constantine adopted the Stedelijk Museum (Amsterdam)'s system of hanging posters rather than rolling them in tubes. Ms. Constantine also developed what she called the Ephemera Collection, letterheads, business cards, etc. collected by the German typographer Jan Tschichold. Constantine wrote scholarly books on subjects like Art Nouveau (in 1959) and Contemporary Package Design (in 1959). Constantine left the Modern in 1971 to independently consult and produce exhibitions, writing books on photography and decorative arts. In 1974, together with Alan Fern, she wrote Revolutionary Soviet Film Posters. The same year Constantine wrote Tina Modotti: A Fragile Life, the first biography of the actress and photographer. She curated the textile exhibitions ''Frontiers in Fiber: The Americans'' in 1988 and ''small Works in Fiber,'' 2002, together with Jack Lenor Larson. A history of fiber in art remained incomplete at the time of her death. She died of heart failure at age 95. Her daughter, Judith Bettelheim, was also an art historian.
- Mildred Constantine papers, 1945-2008, Archives of American Art. https://www.aaa.si.edu/collections/mildred-constantine-papers-15687.