This article is based on a discussion paper prepared for a meeting of the Council on Library and Information Resources on September 27, 1999. Many of the ideas raised at the meeting are reflected in this new version, though naturally I take responsibility for errors and omissions. The meeting was attended by Scott Bennett (Yale University), Pieter Bolman (Academic Press), Robert Bovenschulte (American Chemical Society), Martin Blume (American Physical Society), William Gosling (University of Michigan), Rebecca Graham (Digital Library Federation), Kevin Guthrie (JSTOR), Karen Hunter (Elsevier Science), Michael Keller (Stanford University), Richard Lucier (University of California), Clifford Lynch (Coalition for Networked Information), Deanna Marcum (Council on Library and Information Resources), Elaine Sloan (Columbia University), Abby Smith (Council on Library and Information Resources), Michael Spinella (American Association for the Advancement of Science), Winston Tabb (Library of Congress), Sarah Thomas (Cornell University), Donald Waters (Andrew W. Mellon Foundation) and myself.

This work has been supported in part under DARPA Grant No. N66001-98-1-8908.