[1] She was Executive Secretary to Dr. Leo Kessel (1881–1932) at Mount Sinai Hospital where she organized the follow-up clinic for Graves' disease patients,[2] an experience that contributed to her subsequent reputation for conscientiousness and exactitude.
In 1930 Mayer volunteered at the newly formed Museum of the City of New York, then housed in Gracie Mansion and in 1931 was appointed Curator of Prints there, a position she held until 1959.
Her exhibition of the work of Jacob A. Riis, in 1947, rediscovered the pioneer social documentarian and gained his collection for the museum where it resides alongside more than 10,000 prints and negatives of New York City by the father-son team of Joseph and Percy Byron, taken over half a century, and the Harry T. Peters Collection of Currier & Ives prints.
Source:[2] Mayer wrote articles in the Bulletin of the Museum of the City of New York and in Antiques, Contemporary Photographer, Aperture and Audience.
[12] In 1997, the year after she died, Peter Galassi installed From the Grace M. Mayer Collection, at the Museum; a selection of 35 works from the group she left to the museum, mostly of gifts from photographer friends, including Abbott, Steichen, Manuel Alvarez Bravo, Harry Callahan, Paul Caponigro, Roy DeCarava, Jacques-Henri Lartigue, Helen Levitt, Nathan Lyons, Aaron Siskind, W. Eugene Smith, Paul Strand, Todd Webb and Minor White, as well as lithographs by Toulouse-Lautrec.