How did Greek and Roman historians claim the authority to narrate the deeds embraced by their histories? In this acclaimed and influential book, John Marincola examines all aspects of their self-presentation, surveying the entire field from Herodotus (fifth century BCE) to Ammianus Marcellinus (fourth century CE). He shows how each historian claimed veracity by imitating, modifying, and manipulating the traditions established by his predecessors. After discussing the tension between individuality and imitation, he analyses the recurring style used to establish the historian's authority: how he came to write history; the qualifications brought to the task; the inquiries and efforts he made in his research; and his claims to possess a reliable character. By showing how each historian used the tradition to claim and maintain his own authority, the book – now including a substantial new Introduction – helps us better understand the complex nature of ancient historiography.