Greenbaum is best known for his mixed media assemblage, painting and artist books[4][5] “At a time when most of his contemporaries were calculating how to harden their edges or revamp their styles with the window dressings of Camp, this primal mixed media whizkid from Coney Island labored like an entranced shaman, to conjure up zanily beautiful art brut paintings and weird, wax-drizzled voodoo alter assemblages that resembled nothing so much as the ritual artifacts of some lost psychedelic tribe!”[6]
Greenbaum had several teaching positions in the New York City public school system and was a member of the Creative Artists Public Service program twice, he also participated in various exhibitions with book objects.[16] His work is in several public collections including The Art Institute of Chicago,[17] Artists' Books, The Brooklyn Museum Collection,[5] The Chrysler Museum, Norfolk, VA, Citibank, NYC, Colgate University, Hamilton, NY, Jacksonville Art Museum, Jacksonville, FL, Madison Art Center, Madison, WI, SUNY at New Paltz, NY and more.[citation needed]
"Greenbaum, an early conceptualist, burned books in the 1960s, exhibiting the remains as 'corpses.' Today, he makes fetishistic notebooks filled with colored paper and scribbled equations, accretions of feathers and Rhoplex."[18]
"Marty Greenbaum and Barton Benes destroy texts to create sculpture: Benes 'Bound Book,' a literal rope and wax imprisonment, and Greenbaum's 'Cutting Up,' a mixed media paste over of muted colors."[19]
Some of his most notable artist books include: "Batman" 1963-67,[20] "In '84 Returned in 2004" In Marty's words, "Many techniques and strategies have been used in my mixed media books. By the time of 'In '84 Returned in 2004' I was cutting out shapes and opening up areas in the pages of a finished or an empty book. This device mirrored my sense of movement through space and time, the turning of the pages like a walk through the city, became an exploration of a multidirectional experience, ricocheting back and forth -- the going out and the coming back, the going forward and the return."[21]
1977 Picker Art Gallery, Colgate University, Hamilton NY
1963, 1964, 1965 Stryke Gallery, NYC; In a review of the show, David Bourdon writes: "Marty Greenbaum's work is genuinely messy, crude and seemingly generated by a kind of infantile depravity. The show has the look of a sleazy midway at Coney Island ... It comes on as pathetic, trivial, and awful, and succeeds at being thoroughly enchanting."[23]
1978 Artists' Books U.S.A., traveling exhibition curated by Peter Frank and Martha Wilson[29]
1977 Metamorphosis of the Book, documenta 6, Kassel, Germany;[30][31]Book Objects, Albright-Knox Gallery, Buffalo, NY
1976 Forty Years of American Collage, Buecker & Harpsichords, New York, NY; The Book as Art, Fendrich Gallery, Washington, D.C.; The Object as Poet, National Collection of Fine Arts, Washington, D.C.
1975 Artists Make Toys, The Clocktower, New York, NY[32]
1970 Fur & Feathers, Museum of Contemporary Crafts, New York, NY; Personal Torment/ Human Concern, Whitney Museum of American Art, New York, NY
1968 "Destruction Art," Finch College Museum of Art, New York, NY[33]
1965 "Objects, by Dorothea Baer, Jackie Ferrara, Marty Greenbaum, Lulu, Carolee Schneemann, Van Bovenkamp Gallery, New York, NY[34]
1961 Hall of Issues, Judson Memorial Church, New York, NY[35]