They have caught strangers stealing flowerpots off front porches and lawn mowers out of sheds. Foiled car-theft attempts. And created a network where it seems everyone knows everyone and takes pride in working together to create a common bond.

The neighbors of Burns Street celebrated their sense of community yesterday--gathering in a room at Andrews Air Force Base with family and friends to mark 20 years of keeping their Southeast Washington neighborhood just the way they want it.

Peaceful. Tidy. Free of crime, trash and abandoned cars.

Most of them are now graying, and all are retired--though some have launched second careers. One uses a wheelchair, another a cane. But they still form an impenetrable army around their community on the eastern edge of Fort Dupont Park.

Their weapons? Sharp eyes, porch lights and telephone trees. Their strategy? Peer out the windows--front and back--to see who's on the street or in the well-kept alley. Flick the porch lights at idling cars. Call each other--and police--if someone who doesn't belong is spotted.

"You see anything going on that's not right, you report it to everybody," said Edwina Scott, 68, who last month dialed 911 at 4 a.m. to report a strange car driving up and down the street.

Residents believe the car's occupants stole two ceramic lions from a house a few doors down.

"We have to watch out for each other," said Erzell Brockman, 76. "Out of concern for our neighbors--their concerns are ours."

Brockman is the group's godmother. She first gathered her neighbors together Nov. 10, 1979, to launch a petition drive to convert the 800 block of Burns Street SE from a two-way to a one-way street.

With that rallying point, the group decided to call itself the Neighbors of Burns Street Organization, even though they welcomed residents of adjacent blocks.

They began meeting monthly--to hear crime reports from police and to press city officials for better services--and quickly became known as one of the city's most effective citizen groups.

At the urging of then-Mayor Marion Barry, the Burns Street group joined the fast-growing national Neighborhood Watch movement in 1982 and helped hundreds of other watch groups form citywide.

Unlike the more visible Orange Hat Patrols, in which residents walk through their neighborhoods to frighten away drug dealers, neighborhood watch groups protect their homes from inside by communicating regularly with police and being what Burns Street president Bertie Bowman teasingly calls "nosy neighbors."

The nosiness goes well beyond crime prevention.

D.C. Council Chairman Linda W. Cropp (D-At Large) thanked the Neighbors of Burns Street yesterday for looking out for her mother-in-law after she was stricken with Alzheimer's disease several years ago. Lillian Cropp lived around the corner on Hildreth Street SE and was a longtime group member.

When she needed something, the group provided--or contacted her children. When a traveling salesman made his rounds, neighbors waved him away, warning him not to take advantage.

"You watched and you called and you let us know," Cropp said. "That's what being a good neighbor is all about."

Isaac Fulwood Jr., a former D.C. police chief, who as 6th District commander helped the group get started, joined Cropp at the head table yesterday and said there are few communities like Burns Street anywhere.

"What makes them special is longevity," Fulwood said. "It's 20 years . . . of people who have said, 'We don't accept failure. We're going to do what it takes to make our neighborhood better.' "

The question that loomed yesterday was what the next two decades will bring. Only one of the eight single-family houses on the 800 block of Burns Street has changed ownership since the group was founded. (The "new" owner, there 8 1/2 years, was at the celebration.) And not many people have moved out of the brick duplexes up the block.

Which means stability, but also aging. Most residents of Burns Street are in their sixties and seventies. The eldest, Elijah Claiborne, is 94.

"The block doesn't have any children," said Elaine King Bowman, who with her husband, Bertie, hosted all but the group's first three meetings. "Even the grandchildren are gone."

Well, not completely. Linda Cropp's daughter moved into her grandmother's house after Lillian Cropp went to live with her son and daughter-in-law. Claiborne's nephew lives with him now. Neighbors hope he will stay and raise a new generation of neighbor activists.

Two other children of longtime residents--both young police officers--have purchased their parents' homes. One parks his white-red-and-blue cruiser on the street, to the neighbors' delight. The other was trying to sell recently, but a potential buyer fell through, and Bertie Bowman is lobbying him to remain.

Yesterday's program included a solemn tribute to 15 watch group members--including Brockman's husband and Claiborne's wife--who have died.

As they remembered, some in the room wondered what the future will bring.

Whether tricycles and bicycles will again thread their way up Burns Street SE. Whether youngsters will return to the annual Hot Dog Day on a strip of parkland across from the Bowmans' house, which Elaine Bowman says has turned into a gathering of senior citizens "sitting and eating hot dogs and playing cards."

Whether the younger generation will ensure that the watch group lives on.

"The roots will be here," Brockman said. "And the kids will have to build on that."

CAPTION: Adeline Bolden, left, greets neighbor Elizabeth Moore at the gathering to mark 20 years that a neighborhood watch has kept their community safe.

CAPTION: Elaine King Bowman, center, greets old friends Mary Olsen, left, and Bernice Mungen as they arrive for the party.