In the last decade, literary studies has been dominated by an examination of race, class, and gender as major categories of subjectivity. Recently, however, this almost holy trinity has been challenged and complicated by new considerations---the concept of "nation" in post-colonial studies and "place" in environmental literature. This dissertation argues for the usefulness of another aspect of being, age, as a determiner of identity that does significant cultural work. The project focuses specifically on midlife in nineteenth-century Britain. In contrast to twentieth-century midlife which some theorists argue is dominated by ideologies of decline, Victorian middle age operates as a protean construction that maintains an unresolved competition between gain and loss. I examine ways in which these two conceptions of midlife vie for cultural authority as they are heavily complicated by gender. In the introduction, I discuss age as a construct largely determined by cultural forces but also subject to certain biological constraints, and I provide a brief history of midlife as well as outlining the major characteristics of middle age in the Victorian era. In chapter one, I identify disputes in beauty and conduct books surrounding the performance of youth versus age in regard to midlife markers such as baldness, gray hair, wrinkles, weight gain, and use of cosmetics. Chapter two explores fictive age anxiety, showing that though women are most at risk for aging, portrayals of middle-age angst occur in marriage plots for both men and women. In chapter three, I consider Victorian brides who are middle aged by comparing Frances Trollope's Widow Barnaby with widows in three of Anthony Trollope's Palliser novels. I show notions of decline giving way to increasingly progress-oriented narratives for midlife women. Chapter four examines discourse surrounding "the change of life" for both men and women. The dissertation employs archival materials from beauty and conduct books, as well as medical and longevity texts. Many novels are included that feature midlife, including texts by Frances Trollope, Anthony Trollope, Charles Dickens, George Eliot, Grant Allen, and Margaret Oliphant.