This book addresses how discourses of cultural nationalism and avant-gardism have structured the formation of American poetry canons. Examining William Carlos Williams's importance for postmodern poetry, it underscores how his literary reputation has figured prominently in recent reconsiderations of twentieth-century American literary history. The postmodern poets responding to Williams emphasize not only the cultural politics of constructing literary reputations, but also a more fundamental assumption that governs canon formation, the assumption that "poetic language" excludes speech types marking social difference. Williams's commitment to experimentation and the destruction of traditional forms allies his poetics with the critical stance of the international avant-garde. His writing is especially sensitive, however, to linguistic registers of social difference in the United States. Focusing especially on Williams's early experimentation with poetic form, through Spring and All, but also on his critical and imaginative prose, such as In the American Grain, this book argues that two contingent rhetorical motives structure his response to cultural change: what Lowney calls the "poetics of descent" and the "poetics of dissent."