The surge in immigrants patronizing the Queens system has spurred its branches to offer books, DVDs and CDs in 59 languages, more than double the total a decade ago. So important has acquiring foreign-language books become to the Queens Library’s mission that Radames Suarez, who supervises the Spanish collection, travels every year to the largest Spanish book fair in the world, in Guadalajara, Mexico. The Queens Library even has a staff demographer.

As with bilingual programs that teach students in their native languages as well as in English, the internationalization of neighborhood libraries has led some to question if making foreign books easily accessible impedes or hastens assimilation. Ms. Kim acknowledged that she worried that many Korean immigrants were “reading only Korean books or watching Korean TV or interacting only with Koreans.” Still, she said, in New York “we like to keep our own cultures as well.”

And other librarians argue that making books available in native languages draws immigrants into a library where they will in time browse the English texts.

“As a professional, I think everybody has to have opportunities to read whatever they want,” said Vilma Raquel Daza, the manager of the Corona library, where one-fourth of the books for adults are in Spanish, reflecting a neighborhood whose brick and clapboard houses are dense with Ecuadoreans and other Latin Americans.

While local branches have always had small foreign collections, an ever more multilingual city has led public libraries to dedicate more attention and staff to their effort, grounding decisions in census statistics, reports from foreign title distributors and surveys of branch managers about their patrons.