This PhD thesis consists of two major sections. The critical commentary, Authenticity and alterity: evoking the fourteenth century in fiction, reflects upon issues of authenticity and alterity in historical fiction. The historical novel, The Nature of Things, through its structure, themes, style and language, aims to deliver an authentic and naturalistic portrait of life in the fourteenth century. The commentary and novel are supplemented by a bibliography, and three appendices: a synopsis of the novel, a list of the characters, and a summary of a review of historical novels undertaken alongside the writing, which sought to discover how other novelists addressed the issues of authenticity and alterity. The critical commentary considers what makes good historical fiction, specifically how to bring a sense of authenticity and the role of ‘alterity’. It first addresses the alleged ‘problems’ of historical fiction claimed by nineteenth-century author Henry James and others: the impossibility of authenticity, its innate falsehood, and its failure to portray the past’s strangeness. It then explains the process of writing The Nature of Things: its concept and themes, structure and characters, narrative metaphors, language and style, its quest for authenticity and ‘naturalism’. Then it looks at authenticity in historical fiction and how it can be achieved: through narrative form, recorded history, social context, physical details, and the historical thought-world, including religion and superstition. It goes on to consider the need for, and use of, ‘alterity’ (strangeness) as a means of achieving authenticity, looking at such concepts as magic, spells, the supernatural and monsters. Finally, it looks at the authenticity of language in historical fiction, the relationship between thoughts and words, and the problems of both anachronisms and archaic language. Throughout the commentary, examples are drawn from both The Nature of Things and ther historical novels. Concluding remarks are given at the end. The novel, The Nature of Things, spans the fourteenth century. It is structured in seven parts, each of which is narrated by one of seven different voices. The titles of the parts allude to the four biblical apocalyptic horsemen plus three invented ‘horsemen’ – Poverty, Famine, War, Plague, Death, Dissent, Despair. The titles allude to the disasters that befell the fourteenth century, which form the backdrop for the narrators' stories, but are also metaphors for the narrators’ emotional sensibilities. People's response to disaster is one of the novel’s themes, but so is hope and continuity, expressed in a garden metaphor that is given physical shape in a fictional thirteenth-century gardening book, The Nature of Growing Things.