This dissertation intervenes in a long-standing paradigm that women were largely passive subjects in early medieval society. This passivity has been especially attributed to the strict limitations on women's intellectual and religious authority, and to the resultant silence of Anglo-Saxon and Carolingian women in the extant sources. Numerous scholars such as Valerie Garver, Cristina La Rocca, Régine Le Jan, Rosamond McKitterick, Janet Nelson, and Julia Smith have undertaken dynamic studies to probe this assumption about early medieval women's imposed silence and passivity, finding innovative ways to reveal women's unique contributions to early medieval society and spirituality which had been previously overlooked or misjudged. It is within this groundbreaking tradition of scholarship that this dissertation is situated. This dissertation investigates the heretofore neglected corpus of early medieval women's Latin letters, focusing on two primary features. First, by examining the extant letters written by both men and women, it reveals that elite Carolingian and Anglo-Saxon women were utilizing written correspondence on a scale which has been underestimated by modern scholars. It therefore draws attention to and describes elite women's pervasive and even mundane engagement with epistolary communication, thereby offering a valuable counterpoint to the normative sources from the period which appear to limit women's agency. Secondly, it offers reveals the letters to and from women as decisive evidence of elite women's agency and involvement in politics, culture, economy, and spiritual life in the eighth and ninth centuries. Following an introduction which describes the extant letter collections, and a second chapter in which I contextualize women's letters and letter-writing within the larger corpus of male epistolary activity, I focus on three prominent themes which occur in letters to and from women: petition, gift-exchange, and land and spiritual administration. By unfolding the epistemological significance of these topics and examining individual letters in light of contemporary social, political, economic, and religious conditions of Anglo-Saxon England and Carolingian Europe, I highlight how women were not only engaging with their world, but how these engagements are actually documented through the ephemera of letters.