Anyone who hangs out with me for more than 5 minutes will have to listen to my diatribe on the virtues of regular physical inventory. Shelf by shelf, librarians need to go through the collection and reconcile the the actual physical items to catalog holdings. Naturally, this sounds daunting, but honestly, this is the best prevention on earth if you don't want to be a featured post on Awful Library Books. If every day, professional librarians devoted 15 minutes to a shelf or two of the collection, you would be on the right track to a "clean" collection.
What everyone in your library must embrace is, like weeding, or shelf reading or cleaning, an inventory is never "done". A dynamic collection is just that--dynamic! Therefore, you can't do a weed or an inventory and pronounce it finished. There are new items coming, new sytems, new technologies and the library must keep up.
This is where someone would say "ok lady, I will give you 15 minutes a day-- now what". Never fear, the Practical Librarian is here to help!
Select a collection or obvious "group" of materials. Get a list of materials for that section, group or collection. (No, you don't need a print out of the entire catalog, but you do need a list of stuff that is supposed to be on the shelf where you are doing your inventory) If you need suggestions on places to start try medical, legal, financial, computers/technology and careers.
Now, verify your list to what is on the shelf. If it is checked out, make a note to either request it or check back when it is returned. I found things still checked out on patron records, items in such bad shape I weeded them on the spot, and a few missing items. Every day I pick at a section of the library.
That's it folks! All you need to do is compare the holdings to what is actually in your library and confirm that it actually exists! Everyone can participate! Your boss will love you, your board will love you and your patrons will love you because the catalog says what you really have.
PS As you move through and really get to know your collection, you will be even more amazing at reference and reader advisory!