This article examines the career of pioneer British psychoanalyst David Eder (1865–1936). Credited by Freud as the first practising psychoanalyst in England, active in early British socialism and then a significant figure in Zionism in post-war Palestine, and in between an adventurer in South America, a pioneer in the field of school medicine, and a writer on shell-shock, Eder is a strangely neglected figure in existing historiography. The connections between his interest in medicine, psychoanalysis, socialism and Zionism are also explored. In doing so, this article contributes to our developing understanding of the psychoanalytic culture of early twentieth-century Britain, pointing to its shifting relationship to broader ideology and the practical social and political challenges of the period. The article also reflects on the challenges for both Eder’s contemporaries and his biographers in making sense of such a life.