Digital libraries, whether commercial, public, or personal, lie at the heart of the information society. Yet, research into their long-term viability and the meaningful accessibility of their contents remains in its infancy. In general, as we have pointed out elsewhere, "after more than twenty years of research in digital curation and preservation the actual theories, methods and technologies that can either foster or ensure digital longevity remain startlingly limited." Research led by DigitalPreservationEurope (DPE) and the Digital Preservation Cluster of DELOS has allowed us to refine the key research challenges-theoretical, methodological and technological-that need attention by researchers in digital libraries during the coming five to ten years, if we are to ensure that the materials held in our emerging digital libraries are to remain sustainable, authentic, accessible and understandable over time. Building on 44 S. Ross this work and taking the theoretical framework of archival science as bedrock, this article investigates digital preservation and its foundational role if digital libraries are to have long-term viability at the center of the global information society.