This thesis examines the life and letters of Eliza Louisa Emmerson (1782-1854), a neglected but important correspondent of the poet John Clare (1793-1864). Within a broadly biographical framework, it investigates her side of the correspondence with Clare (his is largely lost), examining her relationships with Clare, his patron Lord Radstock, and S.T. Coleridge's son Derwent and his family. The thesis attempts to correct a number of serious errors and gaps in current knowledge of Emmerson. Chapters 1 and 2 investigate Eliza Emmerson's early life in Bath, family connections with the Bristol poets Chatterton, Coleridge, Southey and Robert Lovell, and early cultural and physical enviromnents, and her marriage to Thomas Emmerson and consequent move to London, showing how the Emmersons' business led them to Clare's future patron, the evangelical philanthropist Lord Radstock, who did much to shape Emmerson's response to Clare. Chapter 3 examines Emmerson's role in the early promotion of Clare. Chapter 4 begins a reading of the letters that passed between Emmerson and Clare, noting the difficulties she faced in mediating Radstock's demands for the moral and political censorship of Clare's poems. Chapter 5 examines Emmerson's involvement, at the behest of Clare's publisher, in editorial work, and her mediation within disputes over the division of profits from Clare's work. Chapter 6 traces Emmerson's role in connecting Clare with the painter Rippingille and the sort of literary circles she was developing around her correspondence with Clare. Chapter 7 looks at Emmerson's editorial work on Clare's poem 'Superstitions Dream' and role in the publication of William Allen's early book about Clare. Chapter 8 follows Emmerson's interactions with Derwent Coleridge, while Chapters 9 and 10 look at later interactions with Clare and Derwent Coleridge, including Emmerson's important role in the editing of Clare's last collection, 'The Rural Muse', and her later life as a reclusive Dante scholar, mirroring Clare's confinement in Northampton asylum.