Despite recent controversies over ‘faked’ memoirs, most readers of life writing continue to trust in the autobiographical pact: they believe that memoirs are a source of personal truth, a writer’s outlet for laying bare the past. But some argue that the codes and conventions of memoir inscribe a distance between self and subject. Before writers are able to tell the truth to their readers, moreover, they have to confront and process that truth themselves over and over again. Writers of autobiographically based fiction (or autofiction, autobiografiction) have long known that the work of truth-telling must start well before publication: the practice of writing in this form demands repeated self-revelation and intimacy with the truth of one’s own life history in a way that memoir may not. In this essay, I embrace the self-reflective methodologies of life-writing practice in order to identify and interrogate the ways in which writers of autobiographically based fiction, including myself, process the truth of their pasts in order to reanimate and rewrite that past via a variety of imagined potentialities. I use a self-reflective analysis of the trajectory of truth-telling in my own writing over time and then turn to examine the work of J. G. Ballard, Virginia Woolf, Katherine Mansfield, Jack Kerouac, and Louisa May Alcott using the revelations in their life writings to produce alternative readings of their fictions. By doing so, I will propose a practical tool for examining that most elusive textual artefact: the writer’s imagination. While the life writing of these writers reveal a single, nominalist, reading of the facts of their lives, that is, their novels demonstrate the power of fiction to unfold hidden potentialities, and further, multiplying facets of truth around those facts. I hope to demonstrate, moreover, the usefulness of the practice-based insights that life writing practitioners can bring to textual analysis as I examine the process of writing autobiographically based fiction from the inside out.