Virginia Woolf ’s diary constitutes the longest and most comprehensive text she ever produced. After finishing The Years, she declared that she would never write another long novel, but she wrote the comment in her diary, already her longest work, and one clearly still in progress. The diary contains all of Woolf ’s conflicts-with her life, her husband, her family, her illness, and her writing. Why was the diary as a form so useful and meaningful to Woolf? In order to contextualize her use and theory of the diary, her own and others, I will explore in this chapter critical commentary on Woolf ’s diary, the diary as a genre, and the diary as a feminine and/or feminist document, as well as put Woolf ’s diary in conversation with two of the greatest diaries, those of Samuel Pepys and Anaïs Nin. Knowing the background and criticism surrounding the genre helps to explain why Woolf was drawn to the diary form and why it proved so congenial to her needs, and seeing how Woolf ’s diary compares to other great ones shows the quality of work Woolf herself produced.