The Data Preservation Alliance for the Social Sciences (Data-PASS) is a partnership of five major U.S. institutions with a strong focus on archiving social science research. The Library of Congress supports the partnership through its National Digital Information Infrastructure and Preservation Program (NDIIPP). The goal of Data-PASS is to acquire and preserve data at risk of being lost to the research community, from opinion polls, voting records, large-scale surveys, and other social science studies. In this paper we discuss the agreements, processes, and infrastructure that provide a foundation for the collaboration. About the Partnership An international movement to archive, preserve, and share data emerged over forty years ago when digital data began to appear in volume. 1 This movement is undergoing a resurgence, as the social sciences shift anew toward a reliance on vast amounts of digital data. Still, we cannot say that even a majority of the digital social science research content created since the revolution in sample surveys and production of digital data has been preserved, nor that newly created data will be preserved. Why is this so? Many corporate and academic researchers assume that data they generate are their property and that they have limited obligations to share their data with others or to ensure its preservation. Some individual researchers are reluctant to deposit their data in archives because they fear competition. Some lack the time or expertise to prepare the metadata required for effective sharing. And some simply do not recognize the long-term value of their data. Institutional data producers may be under legal obligation to protect proprietary information. And some data just falls through the cracks. A huge quantity of digital social science research content lives on, for the moment, solely as files in the computers of individual researchers or of research institutions, or quite possibly as video tapes, floppy disks, or punchcards (etc.) in bookcases, libraries, and warehouses. If research sponsors, producers, and data curators do not take steps to preserve it, it will be lost forever. 2 It needs to be identified, located, assessed, acquired, processed, preserved, and shared. 1 For an history of the early development of this community, see Margaret O Adams, "The Origins and Early Years of IASSIST", IASSIST Quarterly 30 no. 3 (2006), 5-15. 2 The members of this partnership represent the U.S. social science data archives tradition. There are other emerging approaches to preservation, including "self"-archiving, and institutional archiving, and, more recently virtual archiving.