The Creme de la Creme child-care center in Sterling spares few superlatives on its Web site, telling prospective customers that it offers a 21,000-square-foot "magical world" that is a "child's learning paradise."

The center, part of a privately owned chain based in Colorado, greets callers with a cheery bonjour and promises such amenities as a water park, television studio, computer lab and instruction in a second language.

But callers to Creme de la Creme are given a quick reality check when they ask whether they can bring their infant to the center, say, tomorrow.

Of course, there is a waiting list, they are told. And the wait can be as long as eight months.

"For some parents who have to return to work the next week, that's a hard situation to be in," said Maggie Frank, executive director of Creme de la Creme's Sterling center. "I tell parents, 'The sooner you plan, the better.' "

The demand for child care has created a stellar business opportunity in the region, experts in the industry say, both for such large centers as Creme de la Creme, which has a capacity for more than 200 children, and for home-based operations that care for a few children at a time.

The waiting lists at Creme de la Creme and other centers were created by the boom in the region's population -- Loudoun is the fastest-growing county in the nation, according to U.S. Census Bureau statistics -- and by the rise in the number of two-income families, experts say.

"We have a real high crisis demand for infant child care, in particular, because more parents -- and both parents -- are working out of the home," said Beverly Samuel of the Virginia Cooperative Extension's Loudoun office. "The crisis has worsened because of the number of young families in the county who have children. Due to the high cost of living, more families have to have dual incomes. So they may not have a choice of staying home as people typically did years ago."

The demand for child care in Northern Virginia is so great, Samuel said, that "some women have told me they have put their names on child-care waiting lists before they were even pregnant. The people who are savvy and know the child-care situation do that. But not everybody is aware of the shortage."

As recently as 1995, Loudoun had 22 regulated home-based child-care providers. Today it has 150, according to county data. All told, there may be as many as 500 home-based providers in Loudoun, Samuel said. In Virginia, businesses must register with the state only if they care for more than five children at a time, excluding their own. All child-care centers in Loudoun must have local business licenses and zoning permits, Samuel said.

"More people are becoming interested in starting home-based child-care businesses, but there is still a shortage," Samuel said. "We have found there is a high attrition rate among a lot of people who start child-care businesses in their homes. They start the business when they are caring for their own children. But when their own children enter school, they close their businesses. So we need to continually recruit and train providers."

To that end, Samuel offers a three-hour seminar called "Starting a Family Child Care Business." The next session is Oct. 21 at the Loudoun Extension Office in Leesburg. Registration is required.

The business is driven by supply and demand, Samuel said. She said fees are generally lower in western Loudoun, where there is less demand for child care than in the eastern part of the county.

"How much you charge for child care will depend on several things," such as "the established 'going rate' in your community," a handout from the seminar says.

McDonald's, the handout notes, charges more for its Big Macs in "affluent areas."

Creme de la Creme is a decidedly high-end operation that opened in Sterling in late 2002.

"The existence of a place like Creme de la Creme says a lot not only about the growth in this area but the type of people who live in this area," said Mark Henson, a Reston software sales executive whose 6-month-old son, Andrew, is enrolled at the center. "Loudoun now has the types of jobs that can support this type of business."

Mark and his wife, Jennifer, who live in the Cascades section of eastern Loudoun, began their search for a child-care center in August 2003, just after Jennifer learned she was pregnant. Jennifer Henson is an accountant at SLM Corp., a Reston-based firm -- commonly known as Sallie Mae -- that funds and manages student loans.

"What attracted us was not only the infant care at Creme de la Creme but what's available when the child becomes 1, 2, 3 and 4," Mark Henson said. "I like the fact that they start teaching a second language at 2. And they have their own TV station where kids can go in and make television recordings.

"Creme de la Creme is not cheap, I can assure you. It costs as much as a mortgage payment to send your kid there."

The fees range from $1,418 a month for infants to $453 for older children requiring only after-school care, according to Frank, the center's executive director. That includes all supplies, including diapers. Samuel said infant care can cost as little as $700 a month at some centers in the county.

"I joke with my wife that if we didn't have Andrew at Creme de la Creme we could both be driving top-of-the-line Hummers," Henson said. "But for all they provide, we think it's worth it."

Creme de la Creme opened its upscale Sterling center in 2002.Mark Henson, left, and his wife, Jennifer, began searching for a child-care center months before their son, Andrew, was born. Creme de la Creme, which is run by Maggie Frank, right, offers amenities the Hensons appreciate. Jennifer and Mark Henson pick up Andrew from Sashila Simhan, background, who works in the infant room.