The key resource for researching why a particular title was challenged or banned are the publications of ALA's Office for Intellectual Freedom. The Office maintains information on which books are challenged and why and regularly publishes this information in the Journal of Intellectual Freedom and Privacy, where there may also be discussion of the events surrounding a challenge, and in a compilation published about every three years, most recently in Banned Books: Challenging our Freedom to Read, edited by Robert P. Doyle. (Before 2016, similar information was in the Newsletter on Intellectual Freedom.)
Doyle and others used histories of censorship to compile the initial listing of challenged or banned books; this bibliography is in the Guide, as well as included on a list of books on censorship maintained by the ALA Library.
More recent entries are derived from the Journal of Intellectual Freedom and Privacy or Newsletter on Intellectual Freedom.
This publication is available in many libraries around the country, or may be ordered from the ALA Store..
The Banned Books Week pages on the ALA website offer many ways to look at the challenge data that has been collection. The links provided here will be of use to students doing research.
If your library does not have "Banned Books," use the library catalog to locate books on censorship. Useful subject headings are "Challenged books--United States" or "Censorship--United States."
Many libraries offer databases enabling access to periodicals and newspapers. Ask your librarian about accessing these--or visit your library's website, library card in hand, to access.
Use newspaper indexes such as the following to read coverage of book challenges in the communities where they occurred.
Use literature databases such as the following to seek out biographies of authors, book synopses, bibliographies, and critical analysis.
Often, a general web search of < "[book title]" and (banned or challenged) > will yield up useful articles and blog posts about challenges. For example, < "looking for alaska" (banned or challenged) > will bring up newspaper coverage--as well as a video by the author--on the censorship challenges faced by Looking for Alaska, by John Green.