"The atmosphere has a great cross-section of people," said Mike Cardone, 65, of Boston, who has attended nearly every festival since 1972. "The camaraderie between everybody here . . . everybody just gets along."
It is that familial and colorful atmosphere, in addition to the diverse array of folk and rock acts that perform over four days, that makes the festival unique, attendees say.
The Philadelphia Folksong Society, which has been hosting the festival since 1957, expects about 30,000 people to attend this year, including about 7,000 campers. The festival ends Sunday.
Despite the crowds, attendees Saturday said the atmosphere was unusually peaceful for a big-time event, and a major draw in persuading many to return year after year.
"Here's a place where you can spend three days. . . . You can just feel like you're just relaxing and thinking about nothing other than music," Cardone said.
Most spectators lounged on the hill as acts performed on side stages throughout the afternoon, among them Lost Indian, David Amram, and the Amigos Band. The main stage - and many of the tarpaulins laid down in front of it - stayed vacant for the afternoon.
Cardone, sitting on a tarp with his friend Kathi Quinn, 59, of Langhorne, who has been attending for about 20 years, said it was difficult to single out memories. But he agreed with Quinn when she said that "my family knows not to plan a big event" for festival weekend.
"Weddings? Sorry, I have 'Fest,' " she said.
Janessa Smith, 30, from Yardley, said she and her family were attending Saturday to see rock artist Todd Rundgren, who was scheduled to headline on the main stage Saturday night.
Josh Gager, 23, of Atlantic County, said one of the appeals of the festival was getting to watch a variety of artists not typically heard on the radio.
"You definitely get a lot of smaller-name bands that you wouldn't have heard of," he said.
But Gager, like most festival attendees, was particularly enthusiastic about the festival's mellow, collegial atmosphere.
"It's just really nice," he said, adding that in the tent village, campers from different groups often share food and drinks, and occasionally barter for different items.
Frank Wells, 58, fanning his 4-month-old granddaughter as she lay in a stroller, joked that her attendance at such a young age might make her destined to become a festival regular.
"It's in her blood now," he said with a smile.
Contact Chris Palmer at 609-217-8305, firstname.lastname@example.org, or follow on Twitter, @cs_palmer.