Author contributions: T.C.B., P.N.C., and R.P.M. designed research; T.C.B., P.N.C., and R.P.M. performed research; T.C.B. and M.A.W. analyzed data; and T.C.B. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

†Elsevier contested our contract request from Washington State University on the grounds that their pricing policy was a trade secret, and brought suit against the university. The Superior Court judge ruled that Washington State University could release the contracts to us. Elsevier and Springer also contested our request for contracts from the University of Texas (UT) System. The Texas state attorney general opined that the UT System was required to release copies of all of these contracts.

‡Poynder (11) reports that the first contract of this type was signed between Academic Press and the United Kingdom’s Higher Education Funding Council. This contract granted access to the entire portfolio of Academic Press journals for “all higher education establishments in the U.K.” Soon other publishers followed this lead, offering their own multiyear contracts with bundled access. In 2001, Academic Press was purchased by Elsevier from its previous owner, Harcourt.

§Courant and Nielsen (16) estimated that the endowment required to provide the space to keep a 350-page book indefinitely in open stacks is about $130. Based on these calculations, the present value of costs of constructing and maintaining the space required to keep a 2,500-page journal volume permanently on accessible library shelves is roughly $1,000. Courant and Nielsen estimated that costs would be reduced by roughly two-thirds if the book were kept in open stacks for 10 years and then moved to compact storage.

¶For doctoral institutions, we use the terms research 1 and research 2, which were used by Carnegie prior to 2000 and are more widely familiar than Carnegie’s current locutions. Carnegie changed the category names in 2000 and once again in 2005, apparently to appease label-sensitive university administrators. According to Carnegie’s online frequently asked questions, “The Research I & II … categories of doctorate-granting institutions last appeared in the 1994 edition. The use of Roman numerals was discontinued to avoid the inference that the categories signify quality differences.” Our sample of historically based contracts included too few undergraduate colleges to allow reliable estimates of the distribution of prices charged to these institutions.

||We included the National Academy of Sciences although it publishes only one journal, PNAS, because this journal is very large, including more articles than most bundles offered by publishers of multiple journals.

**For publishers that offer no discount for bundled purchases, we treated the relevant bundle as consisting only of those journals listed by Journal Citation Reports.

††Not all journals are included in Journal Citation Reports. There is a lag between introduction of new journals and inclusion in JCR, and some journals do not meet the quality standards set by JCR. An alternative ranking service, Scimago, reports numbers of citations and of articles or academic journals, using less stringent quality thresholds and including more newly started journals. For journals listed by Scimago, and not by JCR, we use Scimago data to estimate annual numbers of citations and articles.

‡‡Blixrud and Strieb (6, 7) report these survey results. Entries in Table 6 are based on tables 1 and 3 in ref. 7. The ARL did not collect statistics on ACS contracts in 2006.