Political action committees are usually associated with large corporations, labor unions, gun lobbies, dairy farmers and a host of other special interest groups.

But now even a neighborhood can have its own PAC. In the Dupont Circle area, a group of 40 residents has formed the Dupont Circle Political Action Committee (DuCPAC) to promote the interests of their neighborhood through political action.

"We join together to use the political process to reward leaders who respect a neighborhood that cares for its residents . . . and to vote out those who oppose us." So states the group's by-laws, in which members also promise to endorse candidates and contribute to their campaigns, to organize voter registration drives and to use "political persuasion."

Dupont Circle activists, concerned about development in their neighborhood, have waged a long battle with the city over planning and zoning policies.

Although people get involved in campaign work before the elections, DuCPAC Treasurer L. Page Maccubbin said, they seldom track the candidates after they are elected to see whether they keep their promises. "We hope to follow through and track these people through the years," he said.

DuCPAC Chairman Bill Treanor said the PAC was an "explicitly political organization." As an example, he cited appointments to the Zoning Commission. "Since we can't elect the Zoning Commission," he said, "we're certainly going to hold the mayor responsible for the zoning commissioners he appoints."

DuCPAC is one of more than 50 PACs registered with the D.C. Office of Campaign Finance. Most are affiliated with a business, professional organization or labor union. Some were set up to support or oppose individual ballot initiatives and are active for relatively brief periods.

DuCPAC appears to be only neighborhood-based PAC in the city. Members of DuCPAC, which was formed last June, pay $10 a year in dues.

DuCPAC leaders say they are concerned about the steady decline in neighborhood population since 1950. They believe the loss of residents is the result of displacement of housing by commercial and nonprofit establishments.

Between 1970 and 1980, the area bounded by Florida Avenue NW, K Street NW, 15th Street NW, and 23rd Street NW lost 23 percent of its population, said Jim Oliver, former chairman of the Dupont Circle Advisory Neighborhood Commission and a member of DuCPAC.

From 1950 to 1980, the population fell from 38,000 to 19,300, a drop of about 50 percent. The figures are from U.S. Census reports.

These kinds of changes, Oliver explained, contribute to the "siege mentality" among those fighting to preserve the neighborhood.

After surveying other organizations in the neighborhood, Bill Rice, chairman of DuCPAC's research committee, warned, "I think the neighborhood is in very grave danger" from development.

Recommendations for protecting residential housing will be a major focus of a community agenda DuCPAC is writing. The group plans to ask 1982 candidates where they stand on the DuPAC objectives before it votes on endorsements.

The committee backed several candidates in last fall's School Board election, including Alaire Rieffel, Ward 2 incumbent. They publicized the endorsement with a mailing to about 800 residents and distributed leaflets at polling places. The committee also gave $200 to Rieffel's campaign.

Despite her loss to R. David Hall, Rieffel claimed that her strong showing in the Dupont Circle precincts was due, in part, to DuPAC efforts. But she noted that she is a resident of the neighborhood, a fact that could have affected the vote.

Treasurer Maccubbin said, "We did very good considering our youth," adding, "It looks to me like we made a difference in our precincts."

DuCPAC members take pride in the diversity of their neighborhood, a diversity reflected in the group's membership. Treanor, a Democrat, served two terms on the D.C. School Board, while vice chairman Joe Grano sought the Republican nomination in 1980 for an at-large seat on the D.C. City Council. Gay activists, veteran political workers, and ANC members are members of DuPAC. J. Ernest E. Harper, the chairman of the Joint Committee on Landmarks, is a member of DuCPAC's executive committee.