Q. How do I find lists of commonly challenged and banned books?

The American Library Association keeps the most comprehensive list of challenged books and why they are challenged.  It is part of an effort to advocate against book banning, so the information they provide does have an agenda associated with it.  Their website is here: http://www.ala.org/ala/issuesadvocacy/banned/index.cfm. 

Below are links to the biannual guides: