Robert Bingham Downs, an author and librarian who spent his career opposing limits on the circulation of books, died Sunday at his home in Urbana, Ill. He was 87 years old.

He died of pneumonia, said his wife, Jane Bliss Downs.

Mr. Downs was dean emeritus of library administration at the University of Illinois. In his 28 years there he helped the library grow to become the third-largest university library in the United States.

A 1929 graduate of Columbia University School of Library Service, Mr. Downs was an outspoken opponent of censorship. In 1953 he was president of the American Library Association.

He was the author or co-author of more than 40 books, including "Books That Changed the World," which was published in 1956 by New American Library and translated into 17 languages. The book sold several million copies. He was a consultant to libraries around the world.

In addition to his wife, he is survived by two daughters from a previous marriage to Elizabeth Crooks Downs, Clara Keller of Salinas, Calif., and Roberta Andre of Avon, Conn.; three grandchildren and two great-grandchildren.