It may take much longer than average to receive certain materials, and some items may not be provided after a request has been made.
Very obscure books and journals may be owned by only a few libraries in the United States. These libraries may charge to lend, or they may not lend at all.
Requests for very old, fragile, unusual, or rare books may not be filled.
Very recent releases of popular books (for example, books suggested by Oprah Winfrey for her book club) may not be provided. This is because all copies may be in use at multiple libraries. There may be long waiting lists for these, and most libraries will put only their own patrons on their waiting lists for books.
Recently published academic books may not be available as many higher education libraries restrict circulation of new acquisitions to their own students, faculty, and staff.
Some libraries do not lend CDs, DVDs, vinyl recordings, microforms, or their students’ dissertations.
Publishers often prohibit Interlibrary Loan lending for articles in the most recent issues of their journals. This is called an "embargo" and it may last from three to eighteen months, depending on the publisher's policies. It can sometimes be challenging to obtain a very recent article from one of these journals.