In conjunction with several federal science agencies, the U.S. National Committee for CODATA organized the Second National Conference on Scientific and Technical Data: Data for Science and Society to address important multidisciplinary issues in managing and using scientific and technical (S&T) data and to improve the visibility of these issues nationally. The main focus was on promoting the availability and usefulness of S&T data to all users, both in research and in the broader society, using examples of ground-breaking and innovative applications and highly creative partnerships. The conference was held on March 13-14, 2000, at the National Academy of Sciences in Washington, D.C., and included a set of plenary presentations by invited speakers, as well as contributed poster presentations and technical demonstrations. These proceedings from the conference include only the invited plenary presentations. These presentations have been edited and reviewed according to standard National Research Council procedures, although they are included in this volume as the contributions of each individual speaker.