Long-Lived Digital Collections. The creation and collection of massive amounts of digital data by the sciences and social sciences today is creating stewardship demands that cannot be met fully by traditional libraries and archive organizations. During the past three decades large, new repositories of digital data have emerged to meet the needs of scientists and of researchers in the social sciences and humanities. Data stewardship is now undertaken by federal agencies, discipline-based consortia of scientists and researchers, supercomputer centers, universities, institutes, and for-profit corporations like ProQuest, ExxonMobil, and Google. Some emerging data repositories have flourished and persisted; others have not. Funded by the National Science Foundation under its Strategic Technologies for Cyberinfrastructure Program, CRL initiated a two-year project to analyze established, "long-lived" collections of data and digital resources, and to create tools and metrics for developing and assessing new repositories.