The National Science Digital Library is devoting significant efforts to provide access to collections of high quality materials to educators. However, the growth and use of the collections is not growing at the rate predicted by early promoters of digital libraries. This project is exploring the use of digital libraries by higher education faculty, examining factors that encourage use of and contribution to these collections. Of equal importance is assessing why faculty do not use materials from digital libraries, with a particular focus on why faculty, who are aware of digital libraries, are not active users. The PI's are conducting focus groups with faculty from the complete range of higher education institutions, from community colleges to research universities, with broad representation across the STEM disciplines. The focus groups are being conducted at scientific disciplinary meetings and at higher education conferences that have significant faculty attendance. The focus groups are providing data for a broad survey of faculty reflecting the geographic, disciplinary, and educational profile of STEM higher education. Results from both the focus groups and survey are being shared with all NSDL projects, and can be used by current and future NSDL projects to understand the needs of current users and to understand and overcome barriers identified by non-users. These data will serve as a baseline for the long-term monitoring of the growth of digital libraries. In addition, the survey is being prepared as a toolkit to allow other projects (including those targeting continuing education and K-12) to modify and use the survey to collect data on their target audiences and better serve them.