Once a month, the San Fernando Library's librarians trade their reading glasses for video-game controllers and invite children to come crank up the volume.

Elias Ponce and about a dozen teenagers shuffle past the stacks of books to the youth section and play "Guitar Hero," a game that lets them pretend they're in a rock band.

"It makes the library a fun place," said Ponce, a 13-year-old eighth-grader who says he now goes to the library every day even when there are no games.

Libraries are turning to video games to connect with teenagers who have outgrown story time. Almost a quarter of libraries surveyed last year by Syracuse University's School of Information Studies had put on video game events.

About half of Los Angeles County's 88 public libraries hold gaming events at least once a month. Administrators credit the practice with helping boost teenage attendance by about 50% since the county started a pilot program two years ago.

The American Library Assn. is giving games its stamp of approval this year. The group designated Friday the first National Gaming @ Your Library Day.

"It lets teens be more comfortable with the library and become familiar with librarians," San Fernando librarian Lydia Harlan said. "And it's what kids are into these days."

That doesn't mean libraries will turn into arcades, said Loriene Roy, the association's president and a professor in the University of Texas at Austin's School of Information. Roy said libraries established themselves as places for both education and entertainment more than a century ago when they created controversy by beginning to lend fiction books.

Now libraries circulate all manner of items other than books, including music albums, tools, toys, cake pans, even animals.

"Libraries are about providing public access to resources, in whatever format," she said. "It goes back to what people want."

Video games are as much in demand as any other form of entertainment, drawing in almost $40 billion in annual sales worldwide. That's more than the recorded music industry and about equal to movie box office revenue. In the United States, two out of three household heads play computer or video games, according to the industry's trade group, the Entertainment Software Assn.

Playing games is the Internet's most popular leisure activity -- more than watching videos and visiting social networking sites such as MySpace, according to technology research firm Parks Associates.

Video game publishers are thankful for the publicity.

"It's a great way to sample our games, and we have found that experiencing our games as a trial often leads to a purchase," said Holly Rockwood, spokeswoman for Electronic Arts Inc., the world's largest video game software company.

For public libraries, games are part of a broader effort to reach out to teenagers.

"Libraries have wonderful children's programs and programs for adults," said Penny Markey, coordinator of youth services for the County of Los Angeles Public Library. "But when it comes to programs serving teens, the numbers drop off. Games help us bridge that gap.

"It's a changing world. Teens are the next adults, the next taxpayers. And the library needs to be seen as an important and relevant resource for them."

Circulation had been declining at the Laguna Hills Technology Branch Library, but it began to edge upward after the facility started holding online game events every Friday night six months ago.

Branch manager Sheila Stone said she wasn't sure that there was a direct correlation, but she noted that the librarians recommend books to the visiting game-players. "So there may be a relationship," she said.

A 2007 survey of 400 U.S. libraries by Syracuse's School of Information Studies found that three-quarters of those who took part in game events returned for other services.