While the Library primarily serves patrons in the state of Maine, it continues to send books by mail to borrowers from all parts of the United States through Inter-Library Loan. Holdings consist of approximately 35,000 volumes covering the field of theology. Areas of strength include biblical studies, theology, ethics, pastoral care, church history, spirituality, and liturgy. The Library is owned and maintained by the Bangor Theological Seminary, and is supported by individual contributions ("Friends of the Library"), as well as by gifts from churches, ecclesiastical groups, and charitable foundations.

Local patrons and members of the former General Theological Library may also submit requests through the Library for materials from the Moulton Library on the Seminary’s Bangor campus. Photocopies of articles from the periodical collections may be obtained for a modest fee. Patrons outside of our primary service areas—Greater Portland and Greater Bangor—are encouraged to request materials through their local library’s Inter-Library Loan department. The Library’s online catalog, accessible through the Seminary’s web site at http://www.bts.edu/, now covers approximately half of the total holdings of the Portland and Bangor libraries.

The Library is generally open Monday through Thursday from 8am to 6:30pm and Friday from 8am to 4:30pm while classes are in session, or Monday through Thursday 8am to 4:30pm and Friday from 8am to 1:30pm during winter and summer breaks. The librarian's hours are Monday through Thursday from 2:30pm to 6:30pm while classes are in session or Monday through Thursday 10am to 2pm during breaks. Due to other staff commitments please call ahead if travelling a distance. Books may be borrowed in person whenever the Library is open. Up to five books may be borrowed at one time.

Members of the former General Theological Library may borrow up to four books per request by mail. Although the Library pays postage to the borrower, contributions to offset the Library's postage costs are welcome. The borrower pays for the return postage. The regular loan period is five weeks. Books for which there is no waiting list may be renewed upon request by telephone or mail. Some reference books are kept in the Library for reference use and hence are not available for loan.

A return mailing label is provided with each book sent out. Borrowers can mail a book back in the same mailer in which it was received if the package was not damaged. Borrowers are entitled to use Library Rate, which is cheaper than Book Rate. Please label the package LIBRARY RATE and use the following U.S. postage rate: