Pack your books into boxes sorted by age. You can put early readers in one box, middle school books in another box and young adult fiction in another. Many charities specialize in a particular age, so sorting the books will make it easier for you to donate them and for the charity to use them.
Contact your local library about opportunities to donate books. Some libraries have book donation programs where they give books to needy children and schools. Even if your library does not have such a program, the librarian will probably be able to give you information about local charities that accept donations. You can also talk to your local bookstore clerk.
Find out how the charities accepting book donations use them. Project Night Night gives books, along with toys and blankets, to homeless kids in shelters. Books for Kids distributes free books to other organizations working with kids to increase literacy. Some nonprofit groups such as the Salvation Army and Goodwill sell book donations as a way to support other programs. Donate to a charity whose vision inspires you.
Check the charity's nonprofit status. Follow the IRS link below and type in the name of the group to find out if it is a legal charity. This is a good thing to do whenever you consider donating to any charity. You want to make sure the organization you give to is what it appears to be.
Write down what you donated and get a receipt. When you make a donation, you can usually get a tax deduction on it. You will need a receipt in case you need to prove to the IRS at tax time that you made the donation.