What happens when the 'modern woman' ages? Modernist Poetics of Ageing answers this question by being the first book-length study of three late modernist women's writers. Drawing on their place within wider modernist networks, this monograph is primarily framed around work by Mina Loy, H.D. and Djuna Barnes, who are often thought of as the quintessentially youthful 'modern woman' of the 1920s. Taking a literary, ageing studies and cultural criticism approach, this monograph focuses on lived experience, as well as thematic representations of ageing in their work, to examine how each author grew older in the years 1940-1982. By surveying literary texts, visual art, photography, life writing and archival material, this book explores the intersection of old age as lived and as well as written to argue that modernist late writing embodies the realities of ageing and transforms them through avant-garde aesthetics. As an interdisciplinary study, this work pairs ageing studies and modernist studies to innovatively consider experimental works written about and in later life. The book suggests that a focus on older age complicates the very avant-garde or modernist aesthetics that each author was interested in: what happens when the scene of the 'new' is populated by older people? How does an embodied experience of illness inform an aesthetics of 'late style'? After fulfilling their role as the youthful 'modern woman' of the 1920s, how did each artist continue to create rich, avant-garde works that go well beyond the paradigms of 'late modernism'? Modernist Poetics of Ageing argues that the late lives of some of modernism's most prominent and networked women writers are overlooked - despite being rich, vital, and contemporary in their continuing commitment to modernist experiment. By reframing these older modernist women writers as engaged in continuing, creative experiments, Modernist Poetics of Ageing reveals that the 'new' does not always have to be 'young'.