The American Library Association’s Office for Intellectual Freedom compiles lists of most frequently challenged books. They do not claim comprehensiveness in recording challenges as research suggests that for each challenge reported there are as many as four or five which go unreported.
How is the list of most challenged books tabulated?

The Office for Intellectual Freedom collects information from two sources: newspapers and reports submitted by individuals, some of whom use the Challenge Reporting Form. All challenges are compiled into a database. Reports of challenges culled from newspapers across the country are compiled in the bimonthly Newsletter on Intellectual Freedom; those reports are then compiled in the Banned Books Week Resource Guide. Challenges reported to the ALA by individuals are kept confidential. In these cases, ALA will release only the title of the book being challenged, the state and the type of institution (school, public library). The name of the institution and its town will not be disclosed.
Where can you find more information on why a particular book was banned?

* Visit your local public library and ask your librarian.
* Find or purchase the latest Banned Books Week Resource Guide, updated every three years, which may be available at or through your local public library.
* E-mail the ALA Office for Intellectual Freedom to ask about a specific book. A staff member will reply with any information the office has on file. Please limit your inquiry to one book. If you would like information on more than one book, please consider purchasing the Banned Books Week Resource Guide.

FMI, contact the Office for Intellectual Freedom at (800) 545-2433, ext. 4220, or oif@ala.org.
– Courtesy of American Library Assocition.