This book argues that Gertrude Stein's gender can best be described as 'transmasculine'. By reading written and visual artefacts of Gertrude Stein's life, this book argues that her gender was 'transmasculine'. Viewing Stein through the lens of transgender theory Chris Coffman reframes earlier scholarship that falsely assumes that Stein's masculinity was a manifestation of self-hatred and misogyny and affirms her masculinity as a vital force in her life rather than a form of false consciousness. In reading Stein's experimental writing, the book pays close attention to the ways Stein's masculinity was formed through her relationship with her feminine partner, Alice B. Toklas, and through what Chris Coffman calls Stein's 'masculine homosocial bonds' with other modernists in her network. This approach broadens out Eve Kosofky Sedgwick's account of 'male homosocial bonding' to include all masculine persons, regardless of physical sex and is used to assess the implications of Stein's relationship to Toklas; other masculine women such as Jane Heap; and men such as Pablo Picasso, Ernest Hemingway and Carl Van Vechten.