Among historians of pre-Conquest England, the life and career of Archbishop Wulfstan I of York (fl. 931–956) has long been overshadowed by those of other, more well-known clerics of the same name. Studies of the period often afford Wulfstan little more than a passing mention, typically as an example of the corruption and secularization that plagued the English church prior to the reforms of the later tenth century. This inattention is somewhat surprising given Wulfstan's participation in many of the most significant events of the mid-tenth century: his twenty-five year tenure – a term longer than that of any other occupant of the diocese between Wulfhere (854–896) and Ælfric Puttoc (1023–1051) – encompassed the collapse of the Viking kingdom of Jórvík, the invasion of Olaf Guthfrithson, the unification of England as a single political entity, and the reigns of kings Æthelstan, Edmund, Eadred, and Eadwig. His influence on the development of the northern Church and at the royal courts of both England and Jórvík made him, as Clare Downham writes, ‘a crucial figure in Northumbrian politics’ and potential ‘king-maker’ for nearly three decades. In large part, the absence of scholarship reflects the paucity of sources: the history of northern Britain during this period is poorly documented, forcing historians seeking even the most basic details of Wulfstan's career to depend primarily on the Worcester (D) recension of the Anglo-Saxon Chronicle and the often unreliable narratives of twelfthand thirteenth-century historians. Moreover, these texts – many of which adopt a distinctively southern bias – frequently cast the archbishop's complex negotiations between the ascendant West Saxon dynasty below the Humber and the faltering Viking kingdom above it in a negative light, in large part influenced by his imprisonment for treason in 952. However, despite Wulfstan's unsavory reputation, those aspects of his episcopate that have attracted the most criticism, his shifting loyalties and entanglement in secular affairs, also make his career a useful lens through which to view the complications and intricacies of tenth-century insular politics.