David Kanter, a corporate lawyer, and his wife, Flora, have been vacationing in Rehoboth Beach for years. Recently, they decided to take the plunge and become homeowners nearby, buying a villa-style single-family house being built at one of the sprawling new residential developments in the once-rural area just inland from Delaware's beach resorts.

The Potomac couple, who are in their early sixties, were looking for a second home that would be attractive enough to lure back their brood of three adult children for holidays. They chose a luxury, golf-oriented waterfront project called the Peninsula on the Indian River Bay, in Millsboro, about 12 miles from Rehoboth Beach. The complex, being built by McLean-based Odyssey Development, is so new that the model homes there were completed over Memorial Day weekend. When the Kanters visited and made their purchase, the site was just farmland.

"It was a leap of faith," Kanter said, adding that his confidence was buoyed because a long-time friend, a bankruptcy lawyer from McLean, was buying a second home there as well, right next door.

Thousands of aging baby boomers are making similar decisions to move to new developments cropping up as fast as corn stalks in coastal eastern Sussex County, Delaware, part of an explosion in the second-home market nationwide. More than a third of all houses sold in the United States now are second properties for their buyers, bought for investment or as vacation dwellings, according to a recent study by the National Association of Realtors. About 85 percent of buyers want homes within 200 miles of their primary homes, which makes mountain and beach locations close to major urban areas primary targets for buyers.

Some people, however, wonder whether the new developments rising near the shoreline are putting the Delaware coast's lazy summertime charm at risk.

The scope of the new projects dwarfs the towns of Rehoboth Beach, Millsboro and Lewes, communities dominated by old-fashioned bungalows and Victorian cottages. The Peninsula on the Indian River Bay will include 1,404 homes, housing more residents than the normal year-round population in nearby Rehoboth Beach. The Plantation Lakes development in Millsboro, which includes 2,500 condominiums, townhouses and single-family homes, will more than triple Millsboro's population over the next decade. When it is completed, the Villages of Five Points outside Lewes will house more people than Lewes, about six miles north of Rehoboth Beach.

"It's mind-boggling to a lot of us," said longtime resident Jody Hudson, a real estate agent who grew up in Lewes. "It's development, after development, after development. It's just overwhelming."

Numerous builders are considering other projects in coastal Sussex County as well, mostly small complexes on major roads. "There's more development there than there has ever been," said Ken Wenhold, Maryland and Virginia director for Metrostudy, a housing research firm based in Houston. "It's been discovered. People are finding out that it is the closest beach -- and it was the most pristine."

The area's appearance is already changing, and the pace of life along with it. Some local residents complain that many of the more visible suburban-style townhouses and condos are little more than unsightly clusters of "beige boxes," with little architectural charm, and that traffic is worsening.

"Most of them are what we call 'barracks on the highway,' because they look like Army barracks -- two to three stories high," said Marnie Laird, 68, a part-time Rehoboth Beach resident whose family has been living or vacationing in the area for three generations. "I think it's destroying Rehoboth. Rehoboth has always been a family place. Now it's hard for families to get here for the weekend because the traffic is so terrible."

Wenhold said that developers are building what most customers want, "a place to crash," he said. "It's all that's being offered because it is the least expensive way to build it. It keeps costs down."

Community activist Mable Granke, a board member of the Rehoboth Beach-based Citizens Action Foundation, said developers are "laughing all the way to the bank" while local officials do little to stop ugly and environmentally destructive developments. Granke, who served on the Montgomery County Planning Board from 1975 to 1986, said that local real estate executives fend off zoning restrictions by charging that any limitations would be unconstitutional violations of owners' property rights. Ten local real estate agencies, for example, co-sponsored a flyer calling a new master plan for Rehoboth Beach a "property rights" issue.

"When I see this happen, it breaks my heart," Granke said. ". . . It's the height of propaganda but people are falling for it."

Larry Goldstein, the McLean-based developer of the Peninsula project, said that land-use controls were noticeably more lenient in Sussex County than he was accustomed to in the Washington suburbs. There were only two public hearings for his project, which places a $13 million golf course on a sweeping stretch of river frontage that wraps around the 800-acre parcel, and a dozen or fewer people attended, mostly just to listen without objection.

He said that state and local officials had been unprepared for the rush of development.

"Delaware was caught by surprise," he said. "They never anticipated these little beach towns would become what they have," he said.

Goldstein said Sussex County officials have no tradition of asking developers to bear some of the expense entailed by new development. He said he offered to give extra money for off-site road improvements to help make sure traffic moves steadily through the area, but that officials said it wouldn't be necessary.

He said one official told him: " 'You've got to be crazy; that's not how we do it in Delaware.' "

New projects are carefully reviewed but are usually approved, said Lawrence Lank, Sussex County's director of planning and zoning, who said the process usually takes a year and includes two public hearings. State officials also review projects that are particularly large or that could injure the environment or cause unusual traffic problems.

The rush of development on Delaware's coast is not unique to Delaware. Environmentalist Jeff Tittel, director of the New Jersey Sierra Club, said large developments are rising along much of the Atlantic Coast.

"Now from the water looking onto the land, you only see houses and development, not trees or dunes anymore," Tittel said. "We're making all the roads going to the beach look like Los Angeles."

But while people debate the issues in public hearings and around kitchen tables, once-pastoral Sussex County is changing rapidly. In 2004, the county issued 3,021 building permits for single-family and multi-family construction, up 78 percent from the 1,695 issued in 2000. Housing permits in 2005 will match or surpass 2004, Lank said.

Part of the reason for the increase is that big developers well known in the Washington area, including Ryan Homes, Toll Brothers, Pulte Homes and Gemcraft Homes, are bringing a new kind of development to the region. Lank said the county favors these large developments because they offer a mix of uses, not just "cookie-cutter subdivisions."

"Three or four years ago, we started to see the big boys come in," Lank said. ". . . What we had before was a farmer sold a lot, a builder got a permit and built a house. Now they are building multi-houses on multi-lots in big projects."

And builders wouldn't be building if buyers weren't buying.

"You can't stop people from moving places, and it's a beautiful place," said Mitchell Cox, 46, a real estate agent from Australia who moved to the Washington area 12 years ago. He and his wife Karen, 43, who is launching a concierge service, just bought a lot at Peninsula and plan to build a $1.6 million custom house there.

"D.C. is the capital of the world right now. It's been the most undervalued, underdeveloped city in the world and it's got a long way to catch up," Cox said, adding that he believes that it is only natural that development would boom around the seaside resorts closest to the city. "You can't stop it, . . . you've got to accept it."

And even the people who move there, and worry about future growth, soon find themselves bringing along their friends and loved ones, just as David Kanter and his long-term colleague encouraged each other to move, buying adjacent houses.

"Reasonable growth is a benefit to all people," said Kanter, whose 3,000-square-foot house in Millsboro will cost about $650,000. "There's always a tug of war between developers and homeowners. I hope there will be a reasonable balance."

His view was shared by Susan Chinnici, 50, of Ellicott City, Md., who recently bought and upgraded a $700,000 vacation home in Rehoboth Beach. She shares it with her husband, chief financial officer of a technology company, and her two teenage children, and she recently talked her sister from Pennsylvania into buying a home there as well. Still, she doesn't want to see too much growth.

"At some point you have to say enough is enough," she said. "You don't want to get rid of the quaintness of Rehoboth."

The Peninsula on the Indian River Bay in Millsboro, Del., is a luxury, golf-oriented waterfront development that is to have 1,404 homes. Construction continues at the Villages of Five Points near Lewes, Del., a beach community of old-fashioned bungalows and Victorian cottages now dominated by new buildings. Looking east toward Lewes, top, and Rehoboth Beach, where seaside developments are crowding out rural areas. "It's mind-boggling to a lot of us," said longtime resident Jody Hudson, a real estate agent who grew up in Lewes. At left, a worker brushes down the exterior of a new building at the Villages of Five Points near Lewes, Del. When completed, the development, with its entrance shown right, will house more people than now live in Lewes.Right, potential buyers are directed to a sales center for the development at Edgewater Park in Rehoboth Beach, Del. A cluster of buildings, above and left, make up the Canal Landing development at Rehoboth Beach. More than a third of all houses sold in the United States now are second properties for their buyers, bought for investment or as vacation homes.