Thousands of people, young and old, converged on Oakland City Hall last spring, crowding into its meeting rooms and filling Frank Ogawa Plaza out front — all for the inaugural Oakland Book Festival.

It’ll happen again on May 22 as the festival returns for its second year. But this year’s will be be even bigger.

Ninety writers took part in 40 events at last year’s festival. This year’s will grow to 200 writers in 60 events, held from 11 a.m. to 6 p.m. Another addition: More than 100 word and musical artists will perform three-minute readings on the plaza’s amphitheater. Also, booksellers and publishers will be back, selling their merchandise at outdoor tables, and the Oakland Public Library will once again host readings at a children’s stage.

Among the historians, journalists, novelists, poets and other authors who will participate are Michael Eric Dyson, Dave Eggers, Pico Iyer, Victor LaValle, Larissa MacFarquhar and Oakland’s own Greil Marcus and Mary Roach. Roach’s latest book, “Grunt: The Curious Science of Humans at War,” is coming out June 7.

Last year’s festival revolved around the theme of cities, exploring such diverse subjects as gentrification and “the genius of the metropolis.” This year the focus will be on labor, with panels taking up income inequality, labor movements, altruism, drug trafficking, sex work, prisons and slavery, and many other topics.

“There is a through line to the OBF,” said Timothy Don, who co-founded the festival with his wife, Kira Brunner Don. “It’s not just a collection of authors reading from their most recent books. It’s a considered and directed event structured around a specific theme that has relevance and repercussions both immediate and local, and historical and national.”

Like last year’s, the festival will be entirely free. As a nonprofit organization, the festival relies on grants and donations and has set up an Indiegogo campaign with a fundraising goal of $25,000.

“You don’t need to buy any tickets or make any reservations in advance,” Don said. “All you need to do is arrive on the day of with an open mind and a willingness to engage with your fellow citizens. The OBF aims to serve and to augment the commonwealth of culture.”

Don added that because many attendees last year didn’t want panels to end — “there was more to say, more to think about!” — several of them will be longer this year. And the panels won’t be limited to authors: also joining in the conversations will be artists, filmmakers and entrepreneurs, including Ellen Pao, the former partner at the venture capital firm Kleiner Perkins Caufield & Byers who was at the heart of a much-publicized gender discrimination case.

“This is a book festival, yes — so there will be plenty of authors on hand,” Don said. “But the OBF is basically a festival of ideas, so we have broadened our reach this year to make room for folks who contribute to the world of ideas in non-literary ways.”

More information: www.oaklandbookfestival.org.

John McMurtrie is the book editor of The San Francisco Chronicle. Email: jmcmurtrie@sfchronicle.com Twitter: @McMurtrieSF