This volume, with an introduction and notes by Emily Thomas, comprises over two hundred selected letters from six philosophers: E. E. Constance Jones, May Sinclair, Karin Costelloe-Stephen, Hilda Oakeley, Susan Stebbing, and Margaret Macdonald. These women were writing during a turbulent period of English thought. Across two world wars, philosophy saw the ebb and flow of idealism, new realism, emergentism, Bergsonism, and logical positivism. The letters, almost all of which are published here for the first time, shed light on the fortunes of all these movements. Many offer fresh philosophical material, helping us understand these thinkers' views on logic, aesthetics, metaphysics, ethics, religion, epistemology, and more. Others contextualize those views: they tell us what these figures were reading; what events they were attending; and where, when, and why they wrote particular philosophical texts. Taken together, these letters also illuminate philosophical networks, sprawling across England and beyond. Although not a single missive between our six women philosophers has survived, this volume shows there were many close connections between them. They discussed each other's work, wrote each other employment references. And these six figures were embedded within a network of women thinkers stretching further still.