Mary Belle Sweet was the University of Idaho's first professionally trained librarian when she was hired in 1905. At 26, Sweet had recently graduated from the University of Illinois Library School.

Unfortunately, soon after her arrival a great tragedy struck the University of Idaho when the library was destroyed in the March 1906 Administration Building fire. The entire library of about 12,000 volumes was completely lost. The library was temporarily housed in the gymnasium and Sweet immediately began re-building the collection, beginning with the 738 books that had been checked out at the time of the fire. Through a dedicated letter-writing campaign, Belle was able to secure over 1000 new books and $1,866 in donations for the library.

Once Ms. Sweet had brought the library back to good health, she began several other initiatives, including the implementation of a card catalog system and the beginning of an archive of Northwest historical materials. This archival collection, first stored in free space behind the stairs, later became the renowned University of Idaho Special Collections and Archives.

At her retirement in 1948, she had compiled the state's largest library for 43 years.