I have 2 librarian who help in keeping the library neat and checking out books. Every book has a sticker on it with a number. I have master list on my computer that tells what book goes with each number. This way we can tell if some are missing and how much they cost. Inside the books, I have little pockets and cards - the same you would find in a regular library book.
Students have to fill it out and give it to the librarian.
The librarian is in charge of checking the books back in. If a student checked a book out and didn't return it or lost it, they must replace it. It seems to work pretty well. This is the downfall to allowing students to take the books home. The up side to all this, the kids always have something to read.