Between 1938 and 1969, the Museum of Modern Art (MoMA) poses the question of What Is Modern? (WIM) in a series of books, traveling exhibitions, and a symposium. This dissertation argues for the WIM project as a sustained if minimally effective effort to influence popular American perceptions of modern art, architecture, and design, at the same time embodying tensions inherent to the museum and its notions of that modernism.

MoMA is an unquestionable influence on modern art history. WIM is a significant component of this influence, yet scholarship on the series is minimal. Hiding in plain sight, the series offers signal insights into the Museum's first century of answers to the question of What Is Modern?

Each WIM holds a key to the development and dissemination of MoMA's ideology. Two versions of What Is Modern Architecture? (WISMA, 1938, 1962) first advocate for and then wrestle with the legacy of International Style architecture. Next, Alfred H. Barr Jr.'s What Is Modern Painting? (WIMP, 1943) and precursors reflect development of the museum's core ideals. At mid-century, Edward Steichen's symposium and unrealized book What Is Modern Photography? (WIMPh, 1950, 1951) fail to critically address the medium upon which the series depends to make its case. At the same time, Edgar J. Kaufmann Jr.'s What Is Modern Design? (WIMD, 1950) and What Is Modern Interior Design? (WISMID, 1953) assert an alternative to the machine aesthetic and International Style ideology. Finally, two versions of What Is Modern Sculpture? (WIMS, 1942, 1969) evince a formalism that, while innovative and provocative in MoMA's early years, read as a conservative statement in the face of late-century art movements and post-colonial attitudes towards "primitivism." The dissertation concludes with a review of media for which the museum chose other (or no) forms of popularization, followed by a review of key themes supporting the central argument.

This investigation draws two interrelated conclusions. First, the WIM series represents a complex and contradictory internal discourse, both within and between departments, over the course of most of the twentieth century, that is subsumed into a confident public education campaign. Second, engagement with modern communications media is integral to the formulation, promulgation—and dissonance—of those notions.