Collect all the books in one spot where you have a lot of room to work. Spread out the books so you can see what you have and start to sort through the collection. Set aside any books that are in need of repair or that need replacing.
Pull out books that are seasonal. Stories about holidays and seasons will only be used at certain times, so keep them separate from the everyday classroom library. Place them in plastic storage containers with lids.
Label the boxes of seasonal books. Use a permanent marker, or print out a paper that can be taped to the boxes. Use general categories as well as sub-categories. For instance, in a box labeled "Fall," list sub-categories such as "leaves," "apples" and "Halloween." ABCTeach.com provides many book genre labels that can be used for the storage boxes as well as on shelves.
Sort non-seasonal books into themes. There can be some carry-over between categories, but try to group books together in a way that will be most useful to you and the students. Examples include alphabet books, counting books, books by Eric Carle, Berenstain Bears books and animal books.
Place groups of books standing up in plastic shoeboxes or bins. Label the boxes and place them on shelves in the classroom. If appropriate, move boxes to different areas of the classroom. A box on cooking could be near the kitchen center, and books about the ocean or fish could be placed near a sensory table with sand and seashells. Encourage the children to engage in reading throughout the room. Place a sticker of a certain color on each box -- and on each book inside a particular box -- so the children can easily put the books away in the correct spot.
Place a selection of books on a book display shelf. If possible, use a shelf that allows the students to see the covers of the books rather than the spines. Children who may not typically spend time reading will be drawn in by an intriguing picture and compelled to pick up the book and look at it.