Dorris Mancuso didn't think twice when she noticed a familiar man watching her from across the street yesterday as she carried groceries into her Germantown apartment. She cracked her front door so she could move her car. But when she came back, her purse was missing.

Mancuso, 72, walked up to the man's apartment and knocked on the door. "Gimme my pocketbook!" she demanded. The man said he didn't have it, so she called members of her neighborhood watch group, and they called the police.

At a National Night Out neighborhood crime-fighting ceremony yesterday, Mancuso said that one woman in the neighborhood watch group offered to pay her bills, and the others offered $100. Montgomery County police searched the man's house and found nothing, Mancuso said. Her group--three women and one man--combed nearby woods for two hours and found her purse, with $276 inside. The thief had taken only $20.

And that, Montgomery County Police Chief Charles A. Moose said, is what community policing programs are all about.

"It's that kind of story that we need to hear about . . . an example that we won't hear too often," Moose told about 300 people in Germantown, adding, "It's really the only chance we have to make a safe community for our kids."

County residents got their first glimpse of Moose, 45, as he appeared at several events for Night Out, a nationwide event featuring block parties, cookouts and parades that promotes better relationships between the police and the community in fighting crime.

In Manassas, residents of the Georgetown South neighborhood who have made strides in trying to erase the area's reputation for crime gathered in the streets at dusk for a three-hour block party.

Moose, a former chief of the Portland, Ore., police department who was sworn in Monday as Montgomery's police chief, was clad in the traditional brown uniform worn by officers as he drove County Executive Douglas M. Duncan and an aide to events in Olney, Germantown and Silver Spring.

Residents said crime in the Germantown area has dropped dramatically in the three years since they united to help push drug dealers out of their neighborhoods.

"I never would have thought a neighborhood watch would have been successful where I lived," Mancuso said.

In the District, about 100 Columbia Heights residents and community center employees drank lemonade, ate cookies and mingled with police officers and city leaders at the Latin American Youth Center, where gunfire erupted more than a month ago between what police said were feuding Hispanic gangs.

Mirna Quinteros, flanked by police and city officials, recounted in a quivering voice last month's gang feud.

She was leaving a party at the community center with about 50 other people, she said, when they heard gunfire. One bullet struck her left leg. Three other bystanders also were shot.

"This really can happen to anyone," said Quinteros, 25, the center's director of education initiatives, balancing on her crutches. "I don't have a rap sheet. I love this community. I grew up in this community. You just never know that this will happen to you."

Evelyn Velasquez, 15, whose leg was grazed by a bullet in the gun battle, urged the crowd to stay committed.

"Let's make sure that we feel safe every night," she said.

Mayor Anthony A. Williams said police are starting initiatives to help in areas like Columbia Heights, citing a $15 million federal grant that will allow the District to hire 200 police officers and the expansion of a program that teams prosecutors with police and residents.

"This is a night to say no to crime and yes to safe, sound, sustainable neighborhoods," he said.

Williams also made stops at other troubled neighborhoods in Southwest, Northwest and Northeast Washington.

At J.O. Wilson Elementary School in Northeast, more than 150 residents attended a cookout to celebrate Night Out.

In April, Williams postponed a news conference at the school when two men who had been wounded in a nearby shooting sought help there just before the mayor was to arrive.

"We've seen some improvements" since the shooting, said the Rev. L.B. Jones II of Pilgrim Baptist Church. "It's just not consistent enough . . . . They [police] have too large of a section of an area and too few men."

But, he said, he was optimistic about Williams's leadership.

"We've got to give him a chance," Jones said. "This problem has been escalating for years. We're not gong to clean it up in 12 months."