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 Presevation 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 unit also deals strategicaly with collections as a whole such as evaluating brittle materials for digital replacement, envirnomental monitoring, collection emergency preparedness, and user education.