This Introduction highlights the importance of this collection - the first of its kind - for showcasing the paradigm-shifting quality of the Anne Lister archive. It describes Lister’s growing importance to a range of disciplines that include the history of sexuality, women’s and gender studies, literary studies, life writing and travel writing. It outlines how Lister’s transgression of gender and sexual boundaries not only marked and shaped every aspect of her lived experience, but also has challenged our understanding of the evolution of sexual and gendered narratives up to the present. Decoding Anne Lister includes interviews and essays on Lister’s queer sexuality and gender variance, her role as a diarist, her pushing of gender barriers through her involvement in local politics and in the managing of her Shibden Hall estate, her adventurous and at times gender-defying travels through Britain, Europe and the Russian Caucasus, and on the highly successful adaptation of the Lister diaries into the BBC/HBO series, Gentleman Jack. Each chapter shows how the Lister diaries have helped to reconfigure the more traditional trajectories of nineteenth-century histories of gender and sexuality, and of social and political life.