From 1976–95 she was Director of the Department of Prints and Illustrated Books at the Museum of Modern Art in Manhattan.
Her father was a printer and progressive activist who shared his love for printing and art with his daughter; passions which informed Castleman's career.
[1] During Castleman's tenure at MoMa, she acquired many works by the world's leading printmakers, including Helen Frankenthaler, Robert Indiana, Jasper Johns, Robert Rauschenberg, Larry Rivers, Edward Ruscha, and Andy Warhol among others.
Riva instituted endowments allocated to print acquisitions for MoMA, an initiative not previously undertaken by any curatorial department at the Museum.
Both of these systems of support established by Castleman for MoMA’s print department have been adopted by other major museums.