The worlds of historians and archivists used to converge around shared understandings of “authoritative” history. This book explores the dramatic changes that have split them apart. Written by an archivist and a historian for the general reader as well as specialists, it shows how shared notions of historical authority and the evidentiary power of archival documentation have given way to radically different approaches to processing the past. New historical thinking, new conceptions of archives, changing notions of historical authority, modifications in archival practices, and new information technologies have opened an “archival divide.” This book situates archives as subjects rather than places of study. It explores how active archivists have long shaped historical knowledge through processes of appraisal, description, and access that have become increasingly contingent and problematic. For historians and those interested in history, the book explains the challenges archivists face in managing both traditional and digital documentation. It examines how archives have traditionally acquired and processed materials deemed “archival” and the changes wrought by the explosive growth of documents of all sorts. For archivists and others, it explores the demands of contemporary historical enquiry, including those relating to social memory, identity politics, and changing conceptions of historical “truth,” and their implications for archival research. For all readers this volume raises the worrisome question of what future historical archives might be like if scholars and archivists no longer understand each other, and indeed, whether their now different notions of what is properly archival and historical will ever again be joined.