Last July 4 Deborah Zanon moved into a three-bedroom town house in Gaithersburg. She had recently turned 25, and she had a mortgage that said the house was hers alone.

"There's no reason for a woman who can afford the payment not to go into buying a house," said Zanon, a sales manager for Metropolitan Life Insurance Co. who earns between $22,000 and $25,000 a year. "With my salary, I had no [income tax] deductions. That's rather silly.

"And now, I don't have to worry about increased rent payments, or getting kicked out, and I can raise a ruckus and have parties if I want."

Young single women homeowners used to be a rarity. In the last decade, however, that has begun to change. Real estate experts say the number of women owning homes and condominiums in the Washington area has skyrocketed and that they are becoming a major factor in the market.

Between 1970 and 1977, the number of single women homeowners living alone in the Washington region jumped by 70 percent, according to recently released data from the U.S. Census Bureau. In Census language, they are "female-headed, one-person households."

During those same seven years, the number of homeowner households headed by women, but with more than one person present, increased 45 percent.

The reasons for the increase in home ownership have to do with many of the same forces that have changed the status of women in other ways:

Federal regulations in effect since the mid-1970s prohibit lenders from discriminating on the basis of sex and marital status, making it easier for women to get mortgage loans.

The escalating rate of divorce has resulted in many "reborn" singles, both men and women.

The "baby boom" generation that is now at home-buying age includes many men and women who have postponed marriage.

More women are working, and being promoted to mid-level jobs accompanied by high salaries.

Audrey Hagedorn recalls that before she came to the Long & Foster real estate company as a manager of its Gaithersburg office in 1974, she had never sold a house to a single woman during the previous five years she had been involed in real estate.

"Now, Hagedorn said, "at least half our sales are to single men and women and unmarried couples, and a fourth of our transactions are with single women."

They are young professionals, recently separated or divorced women, or widows who have been forced to buy more modest houses because their incomes have decreased, she said.

"There's been such a change in the market," Hagedorn added. "Women now have the courage to say, 'Yes, I can buy too. I can get a loan too.'"

While renters throughout the area have lobbied long, hard and some times successfully to limit the spread of condominiums, many single women have found condominiums a relatively low-cost way to provide the tax benefits they seek, fueling their enormous popularity.

Local condominium developer G. V. (Mike) Brenneman said that at two of his projects, one in the Dupont Circle area and the other on upper Connecticut Avenue, two out of every five buyers were single women.

"Unquestionably, there are more single women home buyers now, and the number probably has increased even more since 1977," Brenneman said. "Condominiums probably have gathered the lion's share of single-women buyers, although they're also buying town houses and single-family homes."

In buying property, many women are responding to a fact of Washington social life -- conversations often revolve around real estate.

Grace Murry, 41, a lifelong renter who recently moved here from New York and is buying an Alexandria condominium, said such conversations made her feel left out. "I was tired of hearing people talking about how they had doubled their money," said Murray, a secretary for a nonprofit association. "I thought, 'Why can't that be me?'"

Murray said she earns between $10,000 and $16,000 a year, and used her savings to make a large down payment so her monthly housing costs would be affordable.

"People are tired of renting and having nothing to show for it except rent receipts," Murray said. "I need a tax shelter."

The fact that terms like tax shelter, equity, and investment have become familiar to many women means that the women's movement is growing up, said Emily Womach, chairman of the board and president of the two-year-old Women's National Bank in Washington.

"The women's movement has matured to the point where women are thinking about investments and money, the economics of living, and the independence money can bring," Womach said. "It's all very positive."

The new army of women homeowners range in age from the early 20s -- one woman interviewed is 22 and has owned her town house for two years -- on up.

They include secretaries, nurses, lawyers, journalists and accountants. They are young women who lived at home and saved money to buy, or women who used government programs to help them purchase, or divorcees with children who sold the home they shared with their former husbands and bought new, smaller homes.

Zanon, who is divorced, called buying her first home an "aggravating" experience. But she's already looking forward to buying a second, so she can rent out her current home as an investment.

Mary Sulfstede, packed her bags a year ago and left the apartment she had rented for 11 years in the Dupont Circle area of Washington to buy a condominium in Alexandria, a 40-minute ride by bus and subway from her job in Washington. Now, Sulfstede speaks proudly of how she fixed the leaky toilet in her new bathroom herself -- with the help of a fix-it-yourself guidebook, not a man.

"You're talking to someone who couldn't change a lightbulb before I moved," said Sulftstede, who is in her mid-30s and earns about $20,000 a year as a trade association administrative aide. "I'm beginning to learn."

"I was just tired of renting," Sulfstede said. "Some one-bedrooms rent for over $300 a month. My mortgage is less than what some people pay for efficiency apartments. That's not too smart." She bought a "starter" home only, she added, an investment in the future.

Beverly Grimm, a 27-year-old accountant, has already bought her second house. She sold the house she bought in Ohio in 1977 to buy a town house in Gaithersburg recently.

"Single women feel, 'Well, I'll get a house when I get married.' I've been working for six years. What do I need to wait for? I can afford a house myself," Grimm said.

Before the middle of the last decade, it was not uncommon for some lenders to refuse loans to single women. A study on sex discrimination in housing, published in 1975 by the U.S. Department of Housing and Urban Development, related numerous stories of bias that surfaced during hearings held in several cities in the mid-1970s.

Some testified that single women often were equated with declining property values, and that brokers used to prefer to sell to married couples rather than single women because they felt transactions would proceed more smoothly.

Tom Owen, president of the area's largest savings and loan association, Perpetual Federal, believes the change in lender attitudes was "an evolutionary type of thing," a change that happened when public attention focused on women and their "real or imagined" plight, he said.

"There was no thunderbolt from the executive office," Owen said. "Women are becoming more established financially, better-educated, a younger market -- the same thing that is true of blacks."