This introduction provides the key historical context for the book, outlining the fundamental shift in beliefs about mental illness which transformed insanity from a spiritual to a medical concern in the early nineteenth century. The new physiological concept of madness paved the way for theories of female insanity which were rooted in women’s reproductive biology, through the application of socio-cultural beliefs about women’s maternal role. The main argument of the book is then introduced: that the slippage between ideology and medicine occurred chiefly through written discourse. Writing was the primary way psychiatric theories were formulated, communicated and consolidated during this period and texts are the main site where we see the development of gendered medical beliefs in action. Key forms are identified (psychiatric textbooks, periodicals, and clinical and institutional records), the needs of the developing profession shaping where and how knowledge was articulated.