One of the main roles I have played as a director of the Universal Digital Library has been to write grant proposals to support our work. Both for this project and for another project, Olive.org, an archive of executable content, how to sustain the final product is the most difficult challenge. This paper discusses the various models that might be adopted to sustain a large corpus of digital material, such as that of the Million Book Project. Methods discussed here include government funding, foundations and nonprofits, university homes, and joining existing projects. All individuals working with large digital projects should be concerned about how their work will be kept available to the public. Government funding. Many of the partners in this project have benefited liberally from government funding. The Chinese partners have had significant government support through several successive Ministry of Education five-year plans. The Indian government has supported the project with funding for language translation research projects. The Egyptian government funded the creation of the Bibliotheca Alexandrina and continues to contribute to it. In the U.S., the National Science Foundation supported equipment, travel, and meetings. This support has been essential to the creation of this large corpus of material. The governments very wisely invested in bringing educational and cultural resources to a large segment of their constituents. The disadvantage is that, as government budgets tighten, the funding necessary to sustain a project can be lost. One great advantage of government funding is that the government wants to serve the whole public. Beginning this year, in the U.S., the National Science Foundation now requires principal investigators to explain how the data they have collected will be made available to the larger research community and how it will be sustained. In the U.S., the government also wants free-to-read access and at the same time allows creators to charge for enhanced versions. Foundations and other not-for-profit organizations. Foundations, like the government, are excellent sources of support for the initiation of a large digital project. They have the vision to see what could be accomplished by increasing progress in selected disciplines, such as high-energy physics and astrophysics, and broadening the availability of educational resources. JSTOR and ArtStor are two resources initially supported by the A.W. Mellon Foundation. The Qatar Foundation gave funding to create the Qatar Arabic and Islamic Heritage digital collections. Because that collection so actively reflects the country and region’s culture and because the Qatar Foundation is so focused on educational goals, they are more likely than other foundations to sustain it. Other foundations, such as A.W. Mellon, require that sustainability models be explained before they will fund the initial project. Mellon has been particularly focused on the issue of sustainability. Some electronic products and services found in U.S. academic libraries are licensed through consortia and some come from not-for-profit organizations. One of the more popular ones is JSTOR, a database of articles in journals in a wide variety of fields. Journal of Zhejiang University-SCIENCE C (Computers & Electronics) ISSN 1869-1951 (Print); ISSN 1869-196X (Online) www.zju.edu.cn/jzus; www.springerlink.com E-mail: jzus@zju.edu.cn