Woodstock '99, the three-day musical extravaganza marking the 30th anniversary of the generation-defining 1969 Woodstock festival, was supposed to start today, but performances actually began on Thursday. So, too, did the madness.

Late Thursday night, Parliament-Funkadelic's George Clinton, looking both bizarre and regal in multicolored robes and a bright green caftan, led a massive audience in chants of "Oh yeah! Booty!" Drawn by the thumps and the cheers, thousands of kids streamed across the broad runways at what was once Griffiss Air Force Base to join in. More than a dozen people danced on the top of a parked van painted with psychedelic designs. Nearby, a shirtless boy threw up as his friends looked on, mortified. Meanwhile, at the body-piercing tent, a young woman with freshly pierced genitals was hoisted up in the air by her boyfriend, who held her legs spread so that all could admire her new fashion statement.

This is Woodstock '99. As the event officially unfolded today, no one seemed sure whether this particular Woodstock is defining anything at all. What was clear is that this Woodstock is massive. And very, very hot.

"It's Africa hot," said Greg Aossa, 20, as he emerged from one of the many misting tents, where people went to cool off. "This helps, but just for a while."

"The back of my neck is greasy with sweat and sunblock, which isn't working," said Brian Agosta, 20, as he poured a $4 bottle of water down his back.

Shade was scarce, so people crawled under parked trucks for a break from the sun. Others covered themselves with spare clothing.

Uchenna Egwuonwu, 23, sought relief by taking her clothing off. She strode the grounds wearing nothing but flip-flops and glittery eye shadow. "It's hot. Why not? The body is beautiful," she said. "I've always wanted to walk around in public nude. At Woodstock it's a tradition, so I feel like it's okay. I wouldn't feel safe doing this anywhere else."

Egwuonwu posed for pictures, turned down a proffered balloon filed with nitrous oxide and attracted much attention--almost as much as the guy who wandered around dressed in long black pants, a black shirt and a long black trench coat. As the trench-coated boy drifted by, Eric Bonzar, 20, stared in amazement. "He's probably so geeked up on some drug that he thinks it's snowing," Bonzar said.

By this afternoon, organizers said they had sold more than 200,000 tickets, but they weren't sure how many more. Fortunately, the enormous Griffiss Park seemed big enough to accommodate the crowds.

For some, Griffiss seemed too big. A "People Find" tent aided concert-goers who had lost their companions. Wendy Yonda, 33, a Rochester, N.Y., mortgage originator, brought along her daughter's favorite Teletubby--La-La--impaled on a long stick. "It's a marker. It's hard to find someone in this crowd," she said. "And our daughter will be able to see La-La on pay-per-view."

"They were supposed to have a shuttle," grumbled Drew Hart, 30, a Chicago stock trader with long blond hair. "I came to the last Woodstock, and it was awful. This one is more organized than '94, but for the price of the tickets--$170--we were supposed to have a shuttle between the two stages."

The East Stage and the West Stage are situated more than a mile apart, and even if temperatures weren't well into the 90s, it would seem like a very long walk. "It's on cement and hard-packed, uneven ground," said Hart. He debated whether to walk to the East Stage to hear British soul revivalists Jamiroquai or stay near the West Stage for the grungier sounds of American alternative rockers Buckcherry and Lit. He opted to stay put.

A few lucky festival-goers had brought along Rollerblades or skateboards, which alleviated the transportation problem.

The East Stage was where James Brown opened today's performances, but Brown was not as well received as the comedians who followed him with jokes about Ecstacy and marijuana. Matt Wilkin, 14 and wearing a "South Park" T-shirt, was not impressed by the Godfather of Soul. "He's boring," said Matt. He was waiting for DMX and Limp Bizkit. "I like rap and heavy metal. I don't like this type of music. It's too old."

Today's performers included a variety of acts ranging from rappers DMX and the Roots to pretentious British grunge rockers Bush to Southern California's irreverent punks the Offspring. Upstate New York jam band moe. closed its set with what it referred to as "the national anthem." It was the Ramones's "I Wanna Be Sedated."

Sedated, stoned, drunk--whatever. Maybe everyone was too high or too damned hot to think about the meaning behind Woodstock '99.

Or maybe cultural dissections would have to wait. "It's too early to say," said Ryan Miller, vocalist and guitarist for the Boston trio Guster, which is scheduled to play Saturday afternoon. "Woodstock '94 was about mud and Green Day. I think Saturday's gonna be the day. The bands are more heavy this year. I'm waiting for the barely controlled chaos--everything teetering on the brink of anarchy. How often do you get this many people for an event? Maybe a sports event, maybe when the pope comes to town, or maybe the state fair in Ohio."

"It's nicer than I imagined," said Agosta. "I was kind of scared. I was afraid it would be too rowdy, but it's not too bad. Everyone's very friendly. I don't know much about the first Woodstock, but it seems that this one's going the same way. Everyone's mellow and nice to each other for a change."