This thesis seeks to demonstrate the extent to which secularizing tendencies are present in Russian vitae of the sixteenth and seventeenth centuries, to examine what role these tendencies play in the evolution of sacred life-writing and also consider how they reflect changing perceptions of and attitudes towards sanctity. By the later medieval period, Russian hagiographical writing had evolved beyond the primarily edificatory goals of the early Russian Orthodox Church, and had become a more varied and sophisticated literary medium used to great effect by the hagiographer to present a political, legal, socio-cultural or ideological message which was distinctly secular in nature. Despite the continuing ideological constraints of the Church, hagiographers succeeded in manipulating and refashioning the established patterns of traditional rhetorical vitae in order to express more powerfully an opinion on a variety of non-ecclesiastical affairs. Several native Russian vitae dating to the sixteenth and seventeenth centuries are analysed in detail to demonstrate the development of this tendency in hagiography. The four main chapters of the thesis focus upon different groups of hagiographical works which demonstrate clear evidence of secularizing tendencies: first, vitae composed in northern Russia during the sixteenth century; secondly, works influenced structurally and thematically by oral tradition largely pre- Christian in origin; thirdly, vitae devoted to female protagonists; and finally, seventeenth-century autohagiography. An examination of the relevant historical and socio-political events of the period helps place the vitae chosen for detailed analysis in a wider critical context than simply that of literary genre. Each chapter also includes a section on the contextual hagiographical background which determines the extent to which earlier works of Russian hagiography acted as models or inspiration for the sixteenth- and seventeenth-century vitae.