'Modernist Authenticities' challenges current understandings of modernism by investigating modernist poetry's affinities with surfaces, performances, and materiality. Arguing that modernist writers reference the material body as a source of authenticity and anxiety, this study explores poetry in the context of somatic discourses. Reconsidering Amy Lowell's and William Carlos Williams's poetry, as well as texts by selected other authors, this book suggests that modernism operates with both essentialist and performative conceptions of authenticity. The study proposes that the expansion of the modernist canon in the last decades has still privileged the high modernist paradigm of originality. Authors like Williams and Lowell, who emphasize the theatrical and the performative, were relegated to the margins. Reading Williams's and Lowell's poems in relation to photography and film, expressive culture, and discourses of deviance, this book illuminates modernist literary practices in new ways.