Sarah E. Danca says she runs her own construction firm. The state of Massachusetts says she doesn't.

Unquestionably, her title is president and she owns 55 percent of Danca Co. She does the hiring, the banking, the bookkeeping, the purchasing of supplies and equipment, the final job estimates and some manual labor, sanding, painting and finishing cabinet work in her garage.

But John J. Danca, Sarah's husband, owns 45 percent of the firm. A journeyman carpenter, he long worked for other companies while Sarah Danca raised their three children. Since the couple began the company 10 years ago, John Danca has made the on-site estimates, supervised on-site operations and done carpentry along with 10 employes.

In this age of affirmative action, should Danca Co. get preference for state and federal contracts as a business owned by a woman?

Massachusetts says no, and last year it turned down 84 percent of the firms -- 63 out of 75 -- that applied for state certification as "women-owned businesses." The rejections in effect labeled them fronts for male-owned firms.

"We're not saying every woman is fraudulent," said David Harris Jr., head of the state Office of Minority Business Enterprise. "But many companies blatantly don't meet the requirements . . . . Women have not traditionally been involved in construction."

Across the country, federal and state agencies are beginning to tackle the sexual politics that arise in cracking the old-boy network of government contractors.

Only recently have governments begun to set targets for female participation in multimillion-dollar construction projects such as roads and housing. But bureaucrats are wary, because long-established programs giving preference to firms owned by blacks, Hispanics and other minorities have been plagued by fraud.

"There are tremendous obstacles and frustrations for women-owned businesses trying to get certified in Pennsylvania, Ohio, Michigan, Washington state and all across the country," said Mary A. Johnson, chairman of the Women-Owned Business Committee of the National Association of Women in Construction.

"If you have any male partner, you have to be prepared for an inquisition you wouldn't believe. There's a prejudice that you aren't really running the business."

On the federal level, various agencies, including the Department of Transportation, the Environmental Protection Agency and the Housing and Urban Development Department, reserve business for women contractors. But many federal programs rely on the Small Business Administration (SBA) definition of "socially and economically disadvantaged" companies.

Only a dozen of more than 2,000 SBA-certified companies last year were owned by nonminority women, according to the National Association of Women Government Contractors.

"I agree that just because momma goes to work in daddy's business, that doesn't make her qualify," said the group's president, Karen Olson. "But the SBA consistently attacks every single application by a married woman as a front."

In Massachusetts, a group of irate women contractors, including Danca and other members of the National Association of Women in Construction, complained to Gov. Michael S. Dukakis and is threatening a class-action suit.

"The woman construction company owner has been treated as a front from the outset," said Donna Hardiman, who led the protest. "We were guilty until proven innocent."

According to The Boston Globe, Harris was nearly fired last month as a result of the fuss. Dukakis' chief legal counsel, S. Stephen Rosenfeld, after two meetings with the protesting women, acknowledged in an interview last week that "things were shaking up," but he added that the governor's office is still "looking at the situation."

Harris decries what he calls "efforts to politicize a legitimate process," adding, "If I get fired for doing my job, so be it."

Nonetheless, a few concessions have been made, including the appointment of a woman to the five-member certification board. In the first six months of 1984, a larger share of women applicants was approved, but still barely half -- 23 of 43.

A 1981 Massachusetts law sets aside 5 percent of state building contracts for minority-owned businesses and 5 percent for female-owned businesses. An executive order this year extended the minority set-aside to all state contractors and suppliers, thus matching federal requirements in mass transit and other programs.

According to Harris, more than $100 million a year in state business has been channeled to minority firms and about $2 million to female-owned firms.

The state's regulations for certifying women and minority firms are 44 pages long. But their bottom line in cases like that of Sarah Danca is this: if the man has the resume and the experience -- as John Danca did -- it creates "an irrebuttable presumption that the woman owner does not have dominant control of the company."

That presumption is sexist, female contractors say, because many of them took time out of the job market to raise children and, once they were ready to step back in, it was natural to enlist the aid of male relatives to penetrate an industry notorious for its exclusivity.

The state agency's rules are under challenge in a lawsuit filed by Turnberg Construction, an East Longmeadow firm that was denied certification.

Edward Turnberg owns 80 shares in the company; his wife, Lillian, and his mother, Eleanor, 60 shares each. Like John Danca, Edward Turnberg is in the field, supervising projects, while the women manage the business, including payroll, bonding and banking, according to attorney Stephen Manning.

Protest-leader Hardiman, president of Builders and Vendors Inc., has won over $3 million in subcontracts for state jobs, including several elderly-housing projects, since she was certified four years ago. She had some help from her husband, who once ran a training school for construction companies, but she had an independent track record, too -- a small business refinishing neighbors' basements.

When she applied to be certified, she said, "the agency went through all my canceled checks and made sure I did the bonding, to make certain no man was involved." But she complained that it is wrong to disqualify women because their husbands co-sign checks and bonding papers, because it is common in male-owned businesses for wives to co-sign.

"Construction is a tough, tough business," Hardiman said. "Certification is the key to getting publicly funded work. It gives you that extra leverage. It gives you a couple of good jobs, and that gets you a track record."

The prime contractors, virtually all male-owned companies, "don't like us," Hardiman said, "but they're starting to learn that we're here to stay."