For 38 years, machine tool salesman James P. Fox Jr. has lived in Prince George's County and sat on the sidelines of its political change. And from his viewpoint, Fox doesn't like what he sees: a county pushing aside the needs of middle- and working-class people in its rush to catch up to the upscale development of its suburban neighbors.

So last week, Fox and 27 other members of his predominantly white St. Matthias Roman Catholic Church in Lanham drove 20 miles across the county to the predominantly black Ebenezer A.M.E. Church in Fort Washington to help launch an organization that aims to restructure the balance of political power in Prince George's.

It is a tall order. But the 553 people who were at the founding meeting of the Interfaith Action Communities last Tuesday -- including such religious leaders as Catholic Archbishop James A. Hickey and A.M.E. Bishop John Hurst Adams -- believe that through the collective muscle of 29 local churches they can affect the political process in a way never before experienced in Prince George's County.

"I witnessed the unplanned growth in the county in the '50s, '60s and '70s and all the problems it created," said Fox, 53, a member of the St. Matthias parish council. "I also witnessed the lost opportunities for betterment because of the absence of citizen input. The IAC can . . .interject what we feel are moral decisions into the {political} process."

Interfaith Action Communities was born of concern by some religious leaders that not all county residents are benefiting from rapid development in Prince George's, where construction of 1 million square feet of commercial space began in a three-month period last year.

There are concerns that working- and middle-class people are finding it increasingly difficult to find affordable housing as the push for "executive" development drives up the cost of houses and rent, that the number of homeless families is growing and that inner-Beltway communities are being left to deteriorate as resources and attention focus on the outer suburbs.

"Many good things are happening in our county, but not everyone is coming to share in this bounty," said the Rev. Tom Pollard, pastor of Holy Spirit Roman Catholic Church of Forestville, speaking at the organization meeting at Ebenezer, at which the crowd packed the church's two-tiered sanctuary and spilled into its basement. "It's not just the poor and the needy, but the middle class."

The organization, calling itself the only integrated, broad-based social advocacy group in the county, is patterned after the politically influential BUILD (Baltimoreans United In Leadership Development) group in Baltimore. It emerges at a time when blacks, who make up 46 percent of the Prince George's population, are pushing for a greater share of economic and political power.

It also converges with a budding activism in outer-Beltway areas such as Greenbelt and Bowie, where some civic groups have begun to question the rapid pace of development that is straining roads and other public accommodations, and occurs at a time when older, inner-Beltway communities are demanding more resources to combat a growing drug trade.

Prince George's County Executive Parris Glendening concedes that more needs to be done in areas such as low-cost housing but bristles at the suggestion that county policies have been uncaring. He said a new program to help moderate- and low-income people buy houses will be announced soon, and said the county has made significant increases in recent years in funding for the homeless, the elderly, job training programs and eviction relief.

"The county started with an extensive backlog of needs," Glendening said. "There are a lot of significant needs out there. We have made progress. You can only afford so much."

While ecumenical organizations have operated in the county before -- most recently Prince George's Community Ministries -- Interfaith Action Communities is drawing attention because of the track record of the group that organized it, the radical Industrial Areas Foundation, heir to Saul Alinsky's Chicago-based community organizing effort.

Since its inception in 1941, organizers for the Industrial Areas Foundation have crisscrossed the country helping local churches, civic groups and minority communities create organizations that have prodded, embarrassed and pressured local governments into accepting their activist agendas.

In Baltimore, for instance, in his last months as mayor in 1986, William Donald Schaefer, now Maryland's governor, labeled as unrealistic a BUILD proposal that the city provide home ownership opportunities for 1,000 low-income residents a year, decrease school class sizes to 25 by 1990 and provide a job with benefits for every adult.

A year later, however, after collecting 75,000 signatures on petitions supporting the plan, the group was able to enlist endorsements from all citywide candidates, including Mayor Kurt L. Schmoke, who has promised to make the agenda his own.

The Industrial Areas Foundation also has been successful in New York City, where East Brooklyn Churches since 1980 has registered 10,000 new voters a year, can turn out thousands to a rally and has persuaded the city government to help build 1,057 low-cost houses in Brooklyn. In Texas' Rio Grande Valley, Valley InterFaith claims credit for halting the Environmental Protection Agency's plans to allow the burning of toxic waste in the Gulf of Mexico.

The key to the foundation's success and its enduring quality is the pragmatist view that ordinary people have the capacity to address their own problems, said experts on the Alinsky organizing model.

"The reason they are still around is because they are about something that is fundamentalist -- the idea that there are levers of power you can grab onto if you know how to do it," said Sandford D. Horwitt, an Arlington writer who expects to publish Alinsky's biography this fall.

"They are not conservatives, not radical leftists, not liberals in the usual, conventional way. The issues . . .deal with the quality of life at basic levels: jobs for people without very many choices, houses that people can afford, decent schools," Horwitt said.