Many women wrote philosophy in nineteenth-century Britain, and they wrote across the full range of philosophical topics. Yet these important women thinkers have been left out of the philosophical canon and many of them are barely known today. This book puts them back on the map. The book introduces twelve women philosophers: Mary Shepherd, Harriet Martineau, Ada Lovelace, George Eliot, Frances Power Cobbe, Helena Blavatsky, Julia Wedgwood, Victoria Welby, Arabella Buckley, Annie Besant, Vernon Lee, and Constance Naden. The book examines their views on naturalism, philosophy of mind, the meaning of evolution, morality and religion, and progress in history. The book shows how these women interacted and developed their philosophical views in conversation with one another, not only with their male contemporaries. The rich print and periodical culture enabled these women to publish philosophy in forms accessible to a general readership, despite the restrictions women faced, such as having limited or no access to university education. The book explains how these women became excluded from the history of philosophy because, at the end of the nineteenth century, there was a change towards specialized forms of philosophical writing which depended on academic credentials that were still largely unavailable to women.