“Archiving Otherwise” considers how the documentary mode transforms poetic forms in contemporary book-length poems. The “archival turn” in the twenty-first century has produced a surge in research-based poetry that uses documents like court cases, medical records, news clippings, and letters as what Marianne Moore calls the “raw material of poetry.” These documentary “project books” asymptotically approach their subjects, curating and arranging an array of voices, documents, and forms. Poets attempt the twinned task of filling archival absence and archiving absence in a process I call “archiving otherwise”: they gather new counter-archives or turn the language of the state against itself in acts of détournement. By highlighting how the past is imbricated in the present, gathering the sediment of history, and extending through time and space, book-length documentary poetry practices Édouard Glissant’s “poetics of accumulation.” Reading transnational American documentary poetry written after 9/11, this project attends to the poetry of documentary poetics. The extraliterary discourses documentary poems engage or absorb are not replacing poetic techniques, but catalyzing innovations based on existing poetic forms. The chapters in Part I, “Book-length Cohesion,” address three large-scale structures that turn parts into wholes: momentum through narrative suspense and sonnet networks; frames formed by academic and poetic paratexts; and narrativized argument via anecdotes and what I call “evidentiary arrangement.” Part I reads poems by Tyehimba Jess, Natasha Trethewey, Maggie Nelson, C.D. Wright, BLUNT RESEARCH GROUP, and Claudia Rankine. Part II, “The Poetics of Documentary Rhetoric,” expands this archive to include Anne Carson, M. NourbeSe Philip, Layli Long Soldier, Solmaz Sharif, and Susan Briante. Documentary poetry, like documentary film, is a distinctly public form: it seeks to inform, persuade, and move its audience. Even when it fictionalizes, documentary poetry refers to and makes claims about the world; it asserts language’s power to constitute collectivities and influence actions. The final three chapters locate documentary within the framework of Aristotle’s three branches of rhetoric, pairing ceremonial rhetoric with elegiac apostrophe, courtroom rhetoric with ekphrastic description, and legislative rhetoric with anaphoric repetition. Ultimately, this project shows how documentary is a powerful poetic mode for writing with and against an archive.