who carved out sexology as a new scientific field, are well-known. However, others whose thought was crucial to the field have largely been neglected. The German neurologist Albert Moll (1862Moll ( -1939 is certainly one of them. His name, to be sure, appears frequently in historical works about sexuality, but his life and work warrant more attention than they have received so far. If in the early twentieth century Moll was one of the best-known experts in sexology in Central Europe, his fame had waned by the time he died on 23 September 1939, on the very same day as Freud. His reputation was eclipsed by the widespread adoption of Freud's psychoanalytic theory and by Hirschfeld's prominence as an epoch-making protagonist of sexual reform and the homosexual rights movement. Unlike Freud and Hirschfeld, with whom Moll was engaged in bitter conflicts, he did not establish a school or activist movement. Nor did he ever hold a university position, meaning that he lacked the opportunity to have students and followers who might have taken up and popularized his work.By the 1890s, before Freud, Ellis, and Hirschfeld became influential, Moll had already elaborated the most comprehensive and sophisticated sexual theory to date. But his innovative and ingenious reflections on sexuality, including biological as well as psychological and sociocultural factors, have received far less attention from historians of sexuality and in lesbian and gay studies than those of his contemporaries. When his contributions to sexology are mentioned at all, it is often only in passing and in a one-sided and judgmental way. His antagonism toward the putatively enlightened and progressive views of Freud and Hirschfeld have led many commentators to highlight his political conservatism and regressive views of homosexuality and to therefore overlook his more innovative thinking about sexuality. 1 I am indebted to Gert Hekma, Annette Timm, and two anonymous reviewers for their useful comments on an earlier draft of this article.