For years, little boys with cowboy dreams have grown up to find more mundane work on this little thread of island off the Eastern Shore.

And for centuries, or so the Chincoteaguers say, the ponies have grown up feisty and wild on Assateague, an island stretch of pines and marshes that shelters Chincoteague from the ocean.

Every July since 1925, the men who didn't grow up to be cowboys have had their hour in the saddle, the wild ponies swim to town, the firefighters auction off the foals, and the world, it seems, turns out to watch.

The 35,000 people who lined the shore and streets for the 60th annual pony swim today amounted to 10 times the island's off-season population.

Perched on the bows of motorboats, sprawled in rubber rafts and crammed shoulder to shoulder on the muddy bank of Assateague Channel, they formed a giant arena for the greatest yearly show in town, the "pony penning" made famous in Marguerite Henry's book, "Misty of Chincoteague."

According to the island's old-timers, pony penning began as a way to raise money for a financially strapped fire company. Volunteer firefighters would round up the ponies and herd them across the quarter-mile channel to Chincoteague, where farmers from the mainland bid on them.

The auction still keeps the Chincoteague Volunteer Fire Company afloat, netting as much as $13,000 each year.

Pony penning itself has become an odd blend of island lore and commercial lure, a week to find salesmen hawking plastic models of Misty on Main Street and old-timers reminiscing about how the whole thing started.

"Everyone in Chincoteague takes the whole week off," said Herman Daisey, 65, a volunteer firefighter who has helped round up the ponies since he was 9. "If they're married and moved away, they'll come back. It's more of a homecoming than anything else."

For some non-native Chincoteaguers -- "mainlanders," as they're called here -- today's pony swim was a drama out of the past, a sight that vaulted them back to the days of cowboys and cattle trails.

Maria Manta, 18, watched in awe as 135 ponies plunged into the channel and paddled away from Assateague, their heads held just above the water. A colt the color of wet sand was the first to hoist himself onto the muddy flat of the opposite shore; the others followed, rising with their coats slick, their feathery manes soaked and their ears pointed stiffly back.

"It's like going back in time," Manta said. "Like seeing a roundup."

"It's just the way it was back in the olden time," said Tim Rile, who manages the Plymouth Meeting, Pa., farm where Manta rides. "People just don't do stuff like that any more."

As the ponies clambered onto the shore, shook themselves and began to munch on the dry grass, dozens of cameras clicked in chorus.

"Look at that tiny one just getting out of the water; bless his little heart," one woman murmured from the crowd.

Scores of other spectators perched on rooftops, hung over porch railings and sat in lawn chairs as the firefighters paraded the wild ponies down Main Street, past pastel frame houses and yard sales, past trinket shops and oyster bars and motels.

It is the incongruity of it all that draws some visitors back year after year.

Jim Hanney has been driving down for pony penning from his home in Fairlawn, N.J., since 1975. While the island has changed dramatically in that time, the tradition remains and Hanney likes that.

"Those firemen love the ponies," he said, hoisting his granddaughter Jenneil, 2 1/2, so she could watch the ponies through the slats of a wooden fence. "It's a different way of life here. I appreciate the place."

For some, the mystique of wild ponies is too powerful to leave behind. Michael and Kathy O'Dette drove down from Ashford, Conn., last year and took a $250 colt named Stormy back home with them.

This year, they were scanning the pen for a playmate for Stormy.

"It's intriguing," said Kathy O'Dette as she eyed a filly whose pinto markings, she said, resembled Stormy's. "I look out even now and I think, 'Isn't it amazing, that he was once out here as this wild thing and now he's in my back yard.' "

While tourists gaze into the pony pen and sense something wild and nameless, the longtime volunteers see a distinct, almost human, social order.

C.P. Burns, 72, has been coming from his home near Hagerstown to help with the pony penning since 1950.

"Each stallion has a certain number of mares and he keeps the other stallions away from them," Burns said. "The love life of the horse is just about like the human being."

Dick Griffith, from Richmond, has not missed a pony penning in 40 years. He has come in the off-season, too, and has seen how the ponies warm each other during harsh winters -- standing head to tail, the contours of their bodies close together, the stallion on the windward side to shelter the mare. "They've got more sense than most educated people," Griffith said.

The annual crush of tourists rankles some Chincoteaguers, who worry that the island's popularity will become a curse, driving prices up and longtime residents out.

But pony penning festivities seem to mute the hard feelings and even those who resent the island's changes appear reluctant to spoil the celebration.

"Ever since the day I was born, I wanted to be a cowboy," said C.P. Burns. "I didn't make it, but I sure did try."

Wesley Bloxom, a volunteer firefighter whose face is lined like carved oak, has helped round up the ponies for four decades. When asked why, he shrugs as if the question has never come up, as if the answer wouldn't make any difference.

"I don't know," he says. "It's just tradition to me."