Havelock Ellis' reputation has been in free fall since his death in 1939. Though still acknowledged as a pioneer in the study of human sexuality, he now evokes hostility from those he would have considered his natural heirs. Feminist authors have been particularly critical, identifying him as the kind of friend women would have done well to ignore. While there is no need to put Ellis back on his pedestal, it is clear that recent interpretations underestimate his significance for progressive politics on both sides of the Atlantic. This book examines the many areas to which he contributed (preventive medicine, progressive penology, internationalism, the championing of Ibsen and Nietzsche, as well as feminism and human sexuality) and argues that the vision unifying his endeavors was rooted in the radical generational movement which swept through London in the late nineteenth century. This approach offers both appreciation of Ellis and a richer, more realistic view of the progressive tradition itself.