When it started in the 1960s, the nonprofit Tri-County Community Action Agency in rural Maryland helped low-income families to buy homes using subsidies from the federal Farmers Home Administration.

Now under the gun of cutbacks in federal housing programs under the Reagan administration, the agency has diversified its operations covering Charles, Calvert and St. Mary's counties to become more self-supporting. Tri-County now has its own construction company to build housing for low-income families, has joined a state program to build housing for somewhat-higher-income households, and has syndicated a multifamily apartment development to raise its own subsidy and operating funds.

Another local nonprofit housing organization, Muscle Inc., which operates in the District, has expanded beyond its city-funded technical assistance program for low-income home buyers, into the entrepreneurial field of rehabilitating and reselling vacant apartment houses.

"It's taken us five years to develop the capacity to really go out on our own and develop vacant buildings," Muscle Director Alice U. Vetter said at a conference here this week of the National Neighborhood Coalition, where community groups in housing and other social services assessed how the lean Reagan years have affected them.

Tri-County and Muscle represent a national trend among nonprofit, low-income-housing groups and their response to the current dearth of federal housing aid programs. They have gone beyond their original roles of finding housing for low-income families or advocacy for more progressive government and banking policies.

In their new, more-business-oriented development role, these housing groups are undertaking more diverse programs, branching upward to serve moderate-income households and tapping a variety of funding sources beyond the federal government.

Some nonprofits, as owners of the low-income housing they successfully built in the past 15 years, now are landlords. Where they may have criticized private landlords' practices before, they now have their own concerns about tenants' treatment of their property or disputes with employes.

"It's a major concern now for us to maintain what we have built ; we're dealing with a business," explained Jorge Hernandez, head of a Hispanic community group in Boston that has organized a downtown housing development program.

Although most nonprofit organizations at the coalition's conference saw this entrepreneurship as a healthy trend, many still worry that, as "businesses," they may not retain their role as gadflies pressing for better performance by government and private lenders in low-income neighborhoods.

"We need a balancing of the development role with the organizing role, because without participation of the residents , housing development becomes meaningless," declared Ron Shiffman, director of New York's Pratt Center, which gives financing and design advice to tenant groups.

"Development may be the sophisticated part, but just getting the best-structured deal won't solve the neighborhood problem," said Cicero Wilson, who studies neighborhood revitalization for the American Enterprise Institute. "Things like crime prevention and improvement of local schools which require organizing work are important for real neighborhood improvement."

Michael McCauley, director of the Tri-County Community Action Agency, acknowledged that, as "housing development corporations become more business-oriented, there is a risk of forgetting our roots, to drift away from" resident participation as a major goal.

However, McCauley and others contended that having more sophisticated development programs is not inconsistent with a strong emphasis on neighborhood organizing.

"Community organizing and development are so complementary that the debate on choosing between them should not go on," said Gale Cincotta, director of the Chicago-based National People's Action, a group that has made trailblazing efforts to use the federal Community Reinvestment Act (CRA) to pressure banks into investing in low-income areas.

After years of research and advocacy by Cincotta's organization, neighborhood groups in Chicago have successfully asserted their rights under CRA to force banks to reinvest in declining areas, to correct the years of "redlining" -- the outlining of areas where no loans were made -- that they allegedly pursued.

The result is the "Chicago Partnership," where several large banks have pledged $173 million in loans to low-income neighborhoods in the city for housing and small business. Loans are being made at interest rates equal to the banks' own cost of funds. The banks also have agreed to donate $3 million over the next five years to help the community groups involved increase their expertise.

Under the partnership agreement, the consortium of local nonprofit groups has a right to send representatives to review committees at each bank to help monitor its performance.

Cincotta said that, despite the adversarial roots of the CRA action in Chicago, the partnership is a real one. "It's not just beating up on the banks," she asserted. "We want to show the banks that they can make money by lending in the community."

Hernandez said his community group's experience in Boston reinforces the prospect for partnership with the private sector. "The bankers are less scared of us" than they used to be, and established charities such as the United Way are "getting involved where they never had been before," he said.

Wilson said that corporate donations have been spurred by "the talent they recognize is out there among nonprofit groups."