In a career spanning fifty years, Grossman's illustrations have appeared over 500 times on the covers of various national publications.
For the 1970 comedy recording Don't Crush That Dwarf, Hand Me the Pliers, Grossman painted a quartet of caricatures of The Firesign Theatre.
Rolling Stone magazine issued a series of posters featuring Grossman's cover paintings of George W. Bush, Richard Nixon, Bob Dylan, The Who, Jerry Garcia, and Crosby Stills and Nash.
[10] Throughout his career, Grossman employed an airbrush (he favored compressed air over piston) in order to render the sculptural forms which are his paintings' most readily identified characteristic.
Since with an airbrush a skilled user may lay in areas of shadow and light with either crisp or soft edges, the shapes possess a high degree of visual verisimilitude.
Pete Hamill writing in the international journal of visual communication Graphis[11][12] and Steven Heller in Innovators of American Illustration note that Grossman's approach to the airbrush has been widely imitated.
[13] On the evolution of technique in his illustration, Grossman said, "I was impressed by the way David Levine and the Push Pin artists were using line to develop a bulgy three-dimensional feeling in their work.
"[13] The understanding of form and volume which informs his two-dimensional work finds further expression in an ongoing series of sculptural busts (many of which can be viewed at Grossman's portfolio website).
Unlike most sculpture, they are not intended to be walked around, but are constructed to be photographed from a single point, under particular lighting, printed, and shown to a mass audience.
[18] This grew into the Zoonooz cartoon, which featured a president prone to bumping his head called Gerald Duck, and a Mickey-Mouse-stye movie star Ronald Rodent.
[19] Rolling Stone hosted the regular feature ZooNooz, in which animals enacted a satirical version of current political events.
[13][20] In June 2008, The New York Times published a discussion with Grossman of his political comic strips, which date back to the Kennedy administration.
[20] An occasional essayist, Grossman shared with readers of The Nation his reflections on Art Spiegelman's now-classic graphic novel Maus: "[S]oon one is marveling at the amount of fear, hope, love and pathos that can emerge from a sketch of a mouse's head scarcely a half-inch high.