During the Victorian period, the novel confronted a new definition of human nature that challenged Enlightenment models of individualism. Across a swath of disciplines – not only biology and natural history, but sociology, psychology, theology, moral philosophy, and political economy as well – liberal individualism struggled with the problem of man as a population or species. Writing in a form that had traditionally aimed at forming a household that would in turn reproduce self-governing individuals, Victorian novelists could hardly avoid this problem. To maintain the novel’s preeminence, they had to maintain the individual’s viability in a milieu newly hostile to individualism. Victorian novelists of all stripes responded to this challenge by staging the conflict between individual and species as a conflict between gender and sexuality. In carrying the novel into new areas of modern social and not-so-social life, they also broke it into pieces when serialization began. This change in the mode of publication coincided with the novel’s formal fragmentation into multiple narrators and plots, none of which had an exclusive purchase on truth. As a genre, moreover, the novel devolved into such subgenres as detective fiction, gothic fiction, children’s literature, adventure stories, the novels of the romance revival, and sensation novels, all of which reveal how gender relations – and by proxy liberal society – fail either to encompass or to exclude the populations on which the middle classes were coming to depend. An account of gender and sexuality in the Victorian novel is consequently an account of a conflict that did not yield satisfying resolutions so much as a variety of memorable failures.