In the Main and departmental libraries on the Danforth campus there are over three million print books and journals and a gate count of over one million entrances yearly. Located at the West Campus Library, the Preservation Unit treats many physical materials in the Libraries' collections that suffer damage from use and handling, that are turning brittle with age, or are sent to it for other reasons.

Many of these items are identified at the circulation desk, but not all. For example, Preservation also works with new materials destined for the shelves but needing some treatment first as well as older donated items that are entering the collection.

The Preservation Unit has a Book Repair section that repairs damaged materials sent to it as well as treats newly acquired materials that are not in suitable physical condition for the libraries' shelves without additional treatment.

It also has a Processing section that performs a number of different shelf-ready processing tasks, including making call number labels for new materials, stamping, marking, security stripping, and a Commercial Binding function for items needing journal binding or monograph rebinding, hard digicovers, phase and conservation boxes, and other special bindings.