Liao Yiwu hasn’t been arrested—yet. But the Chinese writer and musician, who served prison time in the 1990s for his work, is currently facing a variety of Chinese censorship measures, including a ban on his books and a travel ban. Mr. Liao has said that the latter restriction was imposed to prevent him from traveling to New York to attend next week’s PEN World Voices Festival of International Literature.

For Larry Siems, the director of the Freedom to Write program at PEN American Center, and his colleagues, the travel ban comes as a double blow. Not only did Mr. Liao write one of Mr. Siems’s favorite books, “The Corpse Walker,” but he was scheduled to be an opening-night guest at the World Voices Festival.

“He’s bringing the experience of contemporary China to the world,” said Mr. Siems. “So banning his books in China and preventing him from traveling is in a sense violating the rights of the Chinese public and the rest of the world to hear what he has to say.”

The weeklong World Voices Festival, which will begin its seventh annual edition on Monday, was launched by Salman Rushdie to address a post-September 11 “dialogue of the deaf” between America and the international community. While Mr. Rushdie, who is retiring this year as chair of the festival, noted that the event has now transcended its original purpose, PEN’s central mission—fighting for freedom of speech—is still paramount.

“The political mood between this country and the rest of the world is not what it was at the time we started the festival—there isn’t so much of a rift in communications,” he said, citing technological advancements in how people connect. But, he added, “it’s established itself as something people find valuable.”

With a new director, 46-year-old Hungarian writer László Jakab Orsós, at the helm, the festival is stretching this year into new and unexpected venues like the High Line, the Standard Hotel and the Westbeth artists residence. Mr. Orsós said he hopes to send the signal that literature is accessible. “It doesn’t occupy this tiny little corner of human culture,” he said. “Wherever you go, you don’t have to go far, and you can consume literature. You can feel part of the contemporary culture.”

It’s the “contemporary” part that PEN wants to accentuate. While the organization does not collect demographic data on its members, “whatever the average age is, it’s too high,” said Dr. Kwame Anthony Appiah, president of the PEN American Center.

The definition of “writer” has expanded significantly in the 90 years since the organization began in London (its American chapter opened a year later, in 1922) with a mission dedicated to aiding “poets, playwrights, essayists, editors, and novelists.” Today, PEN International’s current caseload of more than 700 writers is weighted toward those whose speech is most frequently silenced: journalists, bloggers and activists whose primary medium is the written word.

In Egypt, for example, journalists are more likely to put themselves in harm’s way. “Journalists never stopped criticizing the regime, while novelists continued writing symbolic and vague stories to stay away from the hard teeth of the regime,” said Ekbal Baraka, the director of Egyptian PEN.

Of course, the delivery and impact of the written word has also changed radically since PEN’s inception. In February, the organization’s petition condemning the use of violence against Egyptian protesters garnered 273 signatures; meanwhile, an English-language blogger like Mahmoud Salem, who goes by Sandmonkey, was reaching some 35,000 followers, dozens of times a day, via Twitter. “The web facilitates interactions between individuals and institutions, but you still need institutions,” said Mr. Appiah, citing a coordinated effort by several global PEN chapters to derail a potential United Nations resolution criminalizing blasphemy.

Stephen Hopgood, a professor in the Politics and International Studies department at London’s School of Oriental and African Studies and author of “Keepers of the Flame,” a book about Amnesty International, noted that the generational chasm between older PEN members with a literary bent and potential new recruits is not so easily waived away. “There is now a divide between the class of the members and teenage bloggers and tweeters whose aims and aspirations are not to produce literature,” he said via email.

Still, PEN’s membership criteria remain rigid, stipulating the publication of two books “of a literary character” or one book “of exceptional distinction.” This has kept the organization’s numbers at around 3,400 in America, and 15,000 worldwide, although Mr. Appiah said the rules are currently under review and likely to be modified. Since 2005, PEN America has also offered an Associate Membership option to the general public, which has brought in an additional 912 participants. (By comparison, the human rights group Amnesty International boasts more than three million members in 150 countries.)

But despite its small size and lean operating budget—it spent around $2.8 million last fiscal year—PEN American maintains a diverse array of programs. It runs a prison-writing program, assists writers who have fallen on hard times, provides grants for translation, supports Iraqi refugees who have worked as journalists or “fixers,” and gives out numerous awards with cash prizes. Funding comes largely from benefit events and foundations, and to a lesser degree individual donors and membership dues, which range from $20 to $100.

Compared with other human-rights and civil-liberties groups, PEN’s added value, said Marian Botsford Fraser, chair of International PEN’s Writers in Prison Committee, comes by virtue of its members, many of whom have devoted their careers to thinking and writing about freedom of expression.

“Before, freedom of expression didn’t connect with people as a live issue,” she said. “But I think now that people are experiencing things like the entire internet being shut down in China, in Iran, in Egypt—they actually get it. It’s not about getting your book published. It’s about getting what happened to you in the square a minute ago out there.”