Autobiography is a distinctive and valuable kind of reasoning towards ethical knowledge. But how can autobiography be ethical reasoning? I distinguish four ways in which autobiography can be merely involved in reasoning: as clue to authorial intentions; as container for conventional reasoning; as historical data; and as thought experiment. I then show how autobiography can itself be reasoning by investigating its generic form. Autobiographies are particular, enabling vivid display of and education in value-suffused perception. They are diachronic, enabling critique by ironic contrast. And they are compositional, enabling sense-making by placing in a temporal structure. But these features don’t distinguish autobiographies from novels. Should we therefore accept a deflationary account of a fourth generic feature of autobiographies, that they are self-reflective? I instead pursue a more ambitious account of self-reflection and the distinctively autobiographical reasoning it enables, involving a realism constraint, a reflexive explanation constraint, and unique address to first-person problems of the self. I conclude with an interpretation of an example work of autobiographical reasoning, Siegfried Sassoon’s Memoirs of George Sherston, against the idea that self-owning is necessary to the good human life.