“Sensation Poetry and Social Imagination” unearths a vital but forgotten chapter in the history of British aesthetics, through neglected writings of four major figures: William Hazlitt, John Keats, Arthur Hallam, and Alfred Tennyson. Claims in modern criticism for the social value of aesthetics, like the claim that aesthetics is an ideology enabling exploitation, tend to rely on terms that have evolved from 1890s Aestheticism. This dissertation joins other recent attempts to recover a more textured account of Romanticism’s many and competing ideals of the beautiful in nature and art. It tracks the development of eighteenth-century moral philosophy into early physiology, and reveals surprising motivations behind certain “extreme” or “immature” Romantic experiments with the resources of verse history. Arthur Hallam coined the phrase “sensation poetry” in his famous 1831 Tennyson review to describe poems by Hunt, Keats, Shelley, and the young Tennyson that use novel formal design to emphasize the sensorial effects of reading. From Yeats to Isobel Armstrong, this review has been held up as an anticipation of art-for-art’s-sake ideals, but I contend that Hallam’s theory engages ethical debates that extend back through Hazlitt, Adam Smith, Hartley, Hume, and Shaftesbury. As the belief in innate moral sense became widely challenged in the later decades of the eighteenth century, moral philosophy’s oldest and most vexing question returned with renewed urgency: how can self-interest and benevolence be reconciled? In writing a poetry that, in Keats’s words, must be “proved on the pulses,” sensation poets attempt to show that we are bound together by something more basic than selfhood: the nervous system, and immersion in a shared social world. Hazlitt claimed that our capacity for action—the imagination of future pleasure or pain—also makes it natural to empathize with others in the present. This argument not only contributed to Keats’s theories of poetic imagination, in which the mind is “continually informing and filling some other body,” but also licensed his most radical formal improvisations. My first two chapters show how Keats developed these theories, testing them through thought experiments on dream skepticism, in which the mind cannot distinguish sense from sense-simulation, and through innovations of Augustan couplet style in his longest and most important dream poem, Endymion (1818). My third chapter uses Hallam’s lesser-known writings to show that his famous advocacy of sensation poetry is part of a broad Christian materialism and history of rhyme, which he was developing at the time of his premature death. In Chapter 4 I examine Tennyson’s early imitations of Anacreon, the Greek poet of wine and love. These imitations transpose Italian rhyme contours against eighteenth-century norms for English Anacreontics as a way of affirming Hallam’s belief that enriched English must draw on the sensuous “sources of Southern phraseology” exemplified by Tuscan poets. By placing sensation poetry in a revised history of moral philosophy, and by specifying the resources of verse history this poetry attempted to recover and sustain, my project challenges longstanding assumptions about Romantic aesthetics and the Victorian Aestheticism it inspired. The conceptions of poetry and art I highlight in Hazlitt and Hallam, and in the practices of Keats and Tennyson, return us to a moment before Aestheticism simplified the terms of artistic judgment and moral feeling, and separated art from social life. They represent roads not taken that can help us forge a more sensitive and historically discriminating criticism today.