If you despise disco, hate punk and "new wave" and think the best thing the Beatles ever did was "Rubber Soul," try spending this weekend in Schwenksville, Pennsylvania, to find out that your not alone.

Amid winding roads and small farms they're gathering -- about 8,000 in all -- for the 20th annual Philadelphia Folk Festival, an event that has survived, in its two decades, a hurricane (Carla, in 1971), a visit by a motorcycle gang (1972) and even the initial hostility of conservative neighbors who feared noise, nudity and annoyance. Year after Year, the festival brings in enough money to support the other activities of the Philadelphia Folk Song Society, a nonprofit diversity bound together by a common love of folk music of all stripes: Irish, Cajun, bluegrass, blues, country -- even "contemporary" folk.

This years it's trying to have a little something for everyone: Bo Diddly, Tom Rush, De Danaan (one of the finest exponents of traditional Irish music), the Persuasions (who did a stunning a cappella gospel set last year), the Roches (punk folk, I guess), plenty of bluegrass (Buck White and the Down Home Folks, Bill Harrell and the Virginians, Roger Sprung and the Progressive Bluegrassers), and a host of others -- almost 60 acts over the three days. With its almost 2,500 volunteers and budget of $250,000, it's far from its beginnings in 1962, but it's not Woodstock. An all-festival ticket costs $45, including camping; about 6,000 people camp, and the rest just come for a day.

By 1971, when the remnants of Hurricane Carla swept in at 3 a.m. Saturday, the festival had just moved to its present site, Abe Poole's farm -- fortunately, since its old site on an island in the Perkiomen River was under water. It was still a mess.

The campground is an open field with a dirt road through the middle separating "hevy" camping (vans and the like) from "light" camping (tents). There's a row of portable toilets and a water truck. Organizer Bob Siegel says the "heart" of the festival is in the camping, and that's also where some of the best music is made. After midnight, campers wander about making music, sometimes till the sun comes up.

The campgrounds slope gently down into a grove of trees, and the major stage and three smaller platforms -- used as workshop stages -- are up a hill on the far side of the grove. The slope makes for a natural amphitheater. In front of the main stage are maybe a hundred folding chairs, but most people prefer to spread a blanket on the hill. Two large video screens flank the main stage for those too far back to see, and at the rear are crafts booths, food concessions (run by the local fire departments), a command trailer and a performers' parking lot.

The music goes on almost constantly, from folk dancing at 2 Friday afternoon, the concert from 2:30 till 6 for the early arrivals, through the official opening when piper Bruce Martin, in kilt and full regalia, pipes through the campgrounds and onto the stage on into the 7:30 concert, which must end promptly at midnight.

The cerfew and the strict limit on tickets stem from an agreement made with Upper Saslford Township in 1972, after the township went to court to stop the festival: There had been a few complaints about nudity at the local swimming hole (a refreshing spot down the road) and drug use. The judge ordered the two sides to work out a compromise, which they did: sound off at midnight, limited ticket sales, a contribution to the local fire departments and permission to let them sell food and drink.

The workshops start Saturday at 11 -- a bit early if you've been up all night -- with three stages running at the same time: Here an Irish ceilidh, there banjo-picking, humorous songs and parodies over yonder. Each workshop has about five performers crowded onto its platform, generating an intimacy in lacking in large concerts. There are usually a dozen workshops.

The workshops change from year to year, but some remain constant: always a ceilidh, and a gospel music workshop on Sunday and a children's concert, along with juggling, magic and puppetry to keep the little ones happy. (Children under 12 get in free.)

After the workshop's break up at 4, there's a concert on the main stage at 4:15 -- usually a showcase for less-known performers, though it didn't start out that way. In 1968, the festival had been trying to book Joan Baez, but couldn't; at the last minute, she sent word that she would come. But she didn't want to take the stage away from Odetta, who was appearing that Saturday evening. So a "special event" was arranged, and they've been a feature ever since. The afternoon concert is over at 6, and there's a dinner break until the evening concert at 7:30.

These are complex, with banks of lights and sound gear. In 1975, an electrical storm knocked the sound out. An Irish family dance troupe went on until the sound could be restored; then the lights went out as well. "You could still hear them dancing up there in the blackness," Siegel recalls. "Everyone in the audience pulled out their flashlight and shone it at the stage."

Sunday is a virtual repeat: workshops at 11, concert at 4, break and concert at 7:30. At midnight the festival's over.

In some ways, the festival has become a prisoner of itself, needing money to make money, booking name acts to ensure a healthy draw.

"We did not hire anyone who doesn't have roots in folk or use some folk idiom, even if they are contemporary songwriters," says programmer Teresa Pyott. "Obiviously, a certain number have to be well-known enough . . . but we try to expose [the audience] to some music they wouldn't have heard otherwise."

Tom Rush says the organizers "are a bit sensitive to that perception" of drift away from "pure" folk. "They're booking me this year, Bo Diddley -- they're booking several that do not fall into the traditional music category. . . But they do feel obligated to have a certain number of clog dancers, granola-makers, weavers and the like on the scene. They don't want to be just a music festival. There are families in Ohio that put the kids in the pickup and, by gosh, they come to the Philadelphia Folk Festival."