The Central Square Branch Library at 45 Pearl St. will close Oct. 1 for about three months during the installation of an elevator. The work cannot be done safely while the building is open, officials said.

“While we are very grateful for this investment in the Central Square Branch, we do regret the inconvenience for the neighborhood,” library staff said.

The book drop in the courtyard will remain open. Staff referred patrons needing any other services to the next nearest branches, the Cambridge Main Library, 449 Broadway, and Valente Branch Library, 826 Cambridge St., each about a mile away.