Julie and Jim Jumbelic's daughter Jennifer had three baby sitters before the working couple decided to let a national business conglomerate have the job of caring for their 8-year-old daughter.

"I needed eight hours of day care and I needed eight hours of quality," said Julie Jumbelic of Alexandria, whose daughter and son attend one of the area's 15 Children's World centers, part of a national child care chain.

In the Washington area, parents shopping for child care will increasingly be able to do so among national chains trying to tap one of the nation's largest pools of two-career couples and single working mothers who need child care. In the Washington area, 52 percent of women with young children work outside the home.

"It's quite a booming market," said Dinah McElfresh, spokeswoman for the National Association of Child Care Managers.

But the market is not equal in all areas, according to the experts. The for-profit child care business is growing fastest in Northern Virginia, especially Fairfax County, where industry officials say zoning regulations and reasonably priced land make the situation more attractive than in Maryland and the District.

Few of the national chains plan to do business in the District, where 60,000 children need day care, according to a city government report.

"Land prices in the District are really absolutely prohibitive," said John Quaintance of the Houston-based Daybridge Learning Centers. He said strict zoning regulations in the District and Maryland also make those areas less appealing than Virginia.

Those within the industry say locating in the Washington suburbs is also good business because many parents, who work in the city but live outside of it, prefer to have their children cared for close to home, sparing them the rush-hour commutes.

Custom-built centers with such names as Children's World and Kinder Care are popping up like fast food outlets. These centers emphasize the importance of "quality" care in new facilities with brightly painted rooms and well-equipped playgrounds, hot meals, educational programs and professionally trained staff.

Ann Muscari, vice president of Kinder Care, the largest child care chain in the country with headquarters in Montgomery, Ala., said the number of young middle-class families in Northern Virginia is a tremendous draw.

"Of course it has to do with what people can afford," Muscari said.

"There are many, many affluent two-career families with a strong desire for quality child care," added Jim Reynolds, spokesman for the Gerber Learning Centers, a subsidiary of the baby food company.

Kinder Care and Children's World alone, among the nation's biggest chains, are corporate nannies to more than 7,000 infants and preschoolers in 65 centers in Northern Virginia and Maryland. The two companies plan as many as 50 new centers here in the next five years.

Other chains, such as the Houston-based Daybridge Learning Centers, are to open centers in Northern Virginia next year. Gerber Learning Centers plans to acquire four child care centers in Maryland this week, a spokesman said, and is scouting real estate to build new ones in the future.

Fees at centers such as Children's World, typically sprawling new facilities on half-acres sites, can begin at $72 a week for full-time care for toddlers. Not all of the chains offer infant care, but those that do charge up to $100 a week.

The average cost of full-time day care throughout the Washington area is $65 a week, according to a study by the Washington Metropolitan Council of Governments' child care network.

All licensed day care operators, even the mother looking after a group of children in her home, are required to meet local standards for the number of children per adult, the amount of space per child, and bathroom and eating facilities.

But the profit-making child care industry is going after middle-income, two-career couples who will pay for special services not usually available in independent or nonprofit centers.

At Kinder Care, parents receive daily, written reports on how a child ate, slept and socialized -- even how often diapers were changed.

At the Children's World center, plump couches and chairs in some of the brightly decorated classrooms make the environment homey. Computer and gymnastics classes are available, and day care is more like day camp during the summer, with trips and other special activities. A van takes children in the extended day program to school and picks them up.

Jumbelic's children, ages 8 and 6, attend the Annandale Children's World before and after school. Jumbelic said she likes the convenience of the center's 6:30 a.m. to 6:30 p.m. schedule and the guarantee that care will be available on holidays and in bad weather.

The popularity of the centers and the demand for child care in the area are apparent. Parents in the Hayfield section of Fairfax County started trying to register their children last fall, before the building of a Kinder Care center was begun there.

Waiting lists at Children's World centers, with average enrollments of 125 children, can stretch to five months.

People are reluctant to criticize proprietary child care because of the dire need for the services. But some question whether services or teachers salaries will be cut at the centers in order to assure a healthy bottom line.

Those in the industry say those concerns are unjustified because they must please their customers -- parents -- in order to stay in business. And at an individual center, the corporate image fades in the midst of the bright-faced children.

A small group of toddlers at the Annandale Children's World spent a recent morning pushing toys, knocking over blocks and looking at picture books in an unstructured play session. The adult in charge, known as "Miss Sissy," spent much of her time on the carpeted floor tying shoes and engaging in baby talk.

"Tell those feet to be still, tell them not to get you in trouble," she directed a youngster who preferred running to walking, as she bribed him with a hug.