Irene Masters had had enough of the treadmill, of the frenetic life of a two-career couple. She wanted to stay home with her young daughter.

She couldn't afford to do it in Fairfax County, so last year she and her husband, Gary, gave up their combined income of $95,000 to live on his salary of $55,000, sold their house and moved into an almost identical but much more affordable one in St. Charles, Md., an hour's rush-hour commute from Washington, where her husband works for the U.S. Office of Thrift Supervision.

Twenty-four miles from the Capitol, in what is arguably the most affordable and least well-known of the Washington area's planned communities, Irene Masters is living a 1950s "Leave It to Beaver" life she never dreamed was possible in 1990 -- volunteering, going to exercise classes, taking care of her daughter.

And she is not alone. "Around here, there are a lot of women staying home," she said. "I love it. I absolutely love it. I'm very happy."

On Saturday, St. Charles celebrated its 25th anniversary with a picnic at which the food, like the housing, was affordable. Hot dogs, hamburgers and soft drinks were all priced at 25 cents during the event that drew several thousand -- including an assortment of local politicians -- to a grassy field adjoining the Smallwood Village Shopping Center.

St. Charles, from its inception to today, stands in marked contrast with the self-consciously utopian "new town" of Columbia and with Reston and its towering new downtown. St. Charles has no high-rise center. It has a new mall, Charles Towne Centre, on U.S. 301.

"Reston is a higher-priced community by virtue of its location, design standards, its whole being," said Charles Stuart, senior vice president of Interstate General Corp., the developer of St. Charles. In Columbia, he said, "they decided to create a sociological place. It was billed as a utopian existence."

"This was not a social experiment," he said of St. Charles. "We are not playing a George Bernard Shaw or God or whatever. Our challenge was to build a lot of house and a lot of recreation and a lot of amenities for the lowest possible dollar, to give people the most for their working dollar."

St. Charles does not even have its own post office. Its postmark is simply "Waldorf." And St. Charles Parkway, the community's main thoroughfare, looks like a slightly unkempt country road compared with Columbia's well-manicured Patuxent Parkway.

The still-growing town of 30,000 has another distinction. Unlike the private ventures of Reston and Columbia, St. Charles received an early boost from the federal government under the 1968 housing act.

Announcing a $24 million loan to St. Charles in 1970, an official of the Department of Housing and Urban Development noted the community's special purpose "to provide moderately priced homes rather than to supply housing for the relatively affluent."

St. Charles developer James J. Wilson was the first to seek and the second of 15 to receive assistance under HUD's "new towns" program. Five years later, the program was declared a failure and dismantled. But St. Charles has survived, adhering to its original philosophy.

This is a few-frills, accessible place. Prices of new houses in Reston and Columbia hover as high as $1 million. In St. Charles, the highest-priced detached houses are $200,000 and town houses top out at $130,000.

By design, the 10,000 housing units built so far in St. Charles comprise 2,500 apartments, 2,500 town houses and 5,000 single-family houses. About 8 percent are subsidized for lower-income people. About 10 percent of the population is black, about the same as in Reston and half as much as in Columbia. The average household income in St. Charles is $49,000, less than in its counterparts.

On its silver anniversary, St. Charles is also coming of age politically in Charles County. With the growth of the new town and surrounding areas of Waldorf and LaPlata, the county population has doubled to 100,000 in two decades. On St. Charles's 9,100 sprawling acres, two of its five planned villages are largely completed, and there is an industrial park with such street names as Rockefeller, Carnegie and J.P. Morgan courts.

The new town's growing political importance was evident at Saturday's picnic.

"This place looks more like a political rally than a picnic," said Gregory A. TenEyck, the developer's spokesman. Indeed, candidates for Congress, for sheriff, county commissioner and school board were all present and politicking.

This year there will be five county commissioners instead of three. And with a new residence requirement for candidates, St. Charles will have its own commissioner. So far, two Democrats have entered the field. They are John Acton, who manages one of St. Charles's two village councils, and Robert Fuller, a retired Prince George's firefighter who has served eight years on the Charles County school board. The candidates' issues mirror the problems of growth: crowded schools, inadequate roads and safety.

However they may differ on these issues, the candidates originally came to St. Charles for one reason. "Frankly," said Fuller, "we moved here because it was something we could afford at the time."

Among the candidates at the picnic was William Logan, a retired District police officer running for sheriff. Logan, 43, moved to St. Charles in 1971 and now lives in a five-bedroom house he purchased in 1977 for $58,000. He estimates it would sell now for $140,000. "You can get any type of house here you want," he said. "It's like carte blanche."

Explained IGC's Stuart, "Executive housing is not our goal. Lincoln said the Lord must have loved poor people because he made so many of them. This company is 32 years old, and we've never built an expensive house."