HathiTrust Digital Library was launched in October 2008 as a joint undertaking by 25 research libraries to preserve and provide access to millions of volumes of their digitized holdings. Drawing on the collective experience of the founding members, which include the schools of the Committee on Institutional Cooperation (the Big Ten and the University of Chicago), the University of California system, and the University of Virginia, a robust and scalable infrastructure was created to house, manage, and provide access to the collections. This paper traces the development of the initiative from its origins, describing the challenges it has faced, its strategies for addressing them, and its vision and hopes for the future.