When students in 1924 accused Widener Library administrators of censorship, one librarian at the time called the act a “duty.”

“There are filthy books, salacious books, books corrupting in influence, which it is no part of the library’s duty to distribute to readers,” said the librarian, William C. Lane, according to an editorial in The Crimson that year.

While Harvard’s librarians and the Square’s booksellers no longer yank books from their shelves, they are highlighting controversial books as part of this week’s American Library Association’s “Banned Books Week.”

The Square’s Harvard Book Store currently displays once-banned books ranging from Harper Lee’s “To Kill a Mockingbird” to William Faulkner’s “As I Lay Dying.” Across Massachusetts Avenue, the Coop is showcasing books from “Harry Potter” series, which has received its fair share of controversy.

While the Square’s outlook may sway liberal, other parts of the country can still be somewhat skittish over certain titles. Accordingly, the American Library Association’s “Most Frequently Challenged Books of 2006” was a children’s picture book about the relationship between two male penguins titled “And Tango Makes Three.”

“Typically, in history, censorship has been frivolously and over-extensively applied,” said Lawrence Buell, the Cabot Professor of American Literature. “You look back in a rearview mirror and it’s embarrassing the results. I wouldn’t say censorship is categorically one hundred percent to be prohibited, but it is to be applied with extreme care.”

Jocelyn Chadwick, a former assistant professor at the Harvard Graduate School of Education and the author of “The Jim Dilemma: Reading Race in Huckleberry Finn,” said yesterday that books should never fall under such censorship.

“To censor is to shut down a child’s mind,” she said in a telephone interview yesterday.

Chadwick, who has worked with schools on teaching books that some people deem as too controversial, added that thought-provoking books don’t actually cause the problems that some people fear they do.