Literature of Diminishment redefines regionalism as a philosophical approach that prefers a partial view of oneself and of others, whether human or nonhuman, rather than the comprehensive view pursued by nineteenth-century science. I show how American regionalist writings from the 1820s to 1910s adapt scientific techniques of observation to the aesthetics of the regionalist sketch. Their "sketchy" view of Nature highlights the deficiencies of knowing and nonetheless opens out to a view of biological processes and succession in which life cedes to life through its casualties. Regionalist literature is, then, less a literature of particular cultural or geographical regions as it is a literature whose principles of diminishment might insist on the roughness and limits of a regional setting. The archive of works I draw upon extends from environmental literature-the nature writings of John James Audubon, Henry David Thoreau, and Celia Thaxter-to less conventionally regionalist texts of the nineteenth and early twentieth centuries such as works by Emily Dickinson, Herman Melville, W.E.B. Du Bois, and Gertrude Stein.In regionalist formulations, diminishment is a mode of seeing that relies on imprecise and partial specifications rather than strict definitions. Understanding art and science as approaches that both connote ways of seeing and being in the world, I show how writers like Thoreau, Dickinson, Melville, Thaxter, and Sarah Orne Jewett experiment with partial ways of seeing through concomitantly aesthetic and scientific uses of views, optics, and visual technology. Setting the frame with Thoreau's vista from the eroding shores of Cape Cod, I consider how these writers' engagement with natural history's empirical methods attends to their own perceptual diminishment, and also, critically, to the diminishment of their object of study-Nature, or, more generally, life. The final chapters examine the practice and politics of seeing human races as "species," that is, as part of nature, through what I consider "snapshots" of black workers. Du Bois's and Stein's literary-photographic studies view and review the racialist natural history that pictures African-Americans, as Du Bois writes, "somewhere between men and cattle." Regionalism, I argue, instead affords the succession of life through diminishment, rather than a reduction of life to units of data.