An elderly woman stands behind the screen door of her Chapin Street NW home, staring into the crisp winter morning. A boy with a book satchel ambles past, whistling a tune as he heads for school. After nearly five years of gun battles, police chases and countless curbside marijuana transactions, Chapin Street is--for now--a quiet residential enclave once again.

The latest police effort: a residential blockade. The result is that drug trafficking is much less visible. It continues, however, behind closed doors.

"We just closed off the street," said Sgt. Roy Crogan, a D.C. police vice squad detective. "If you don't live on the block, you don't get in unless you're going to visit someone. In that case, we have a policeman escort you to the door."

A month ago, the 3rd District's tactical unit began assigning officers to maintain a day-long vigil, using a large van and two sawhorses, at the entrance of the block-long street, which runs between 15th and 14th streets NW.

"We think it's fantastic," said Marianne Davis, cochairwoman of the Chapin Street Citizens Association. "We have been petitioning the police to make every effort to return our streets to us and we are so pleased with their latest effort. It's not perfect, but it has made an enormous reduction in the number of drug dealers and buyers who had taken over and turned our homes into prisons."

In previous years, Chapin Street traffic often was backed up bumper-to-bumper as youths showing Dale Carnegie-style initiative worked the curbsides, flashing five fingers, meaning $5, as they hawked their wares. "Gold, gold. Got that gold," was a popular refrain advertising the sale of high-quality marijuana known as Acapulco Gold.

In the fall of 1981, police for a while tried to discredit the sellers with a tactic known as "Operation Oregano." Four undercover officers joined the crowd with bags of bitter spices and tasteless leaves and also took up the chant, "Gold, gold. Got that gold."

This approach led to more trouble as irate customers returned for revenge. Meanwhile, bonafide marijuana sellers continued to ply their trade.

Later, Chapin Street was turned into a one-way drive, heading east toward 14th Street. The result: bumper-to-bumper traffic, one way.

Today, the entrance to the street resembles the checkpoint at a small military installation.

Cars approaching the intersection, which is across from Meridian Hill Park, are waved to a halt and drivers and passengers are asked to show identification before being allowed to enter.

"Most of the reaction is positive, because most of the people we stop live here," said Officer Sterling Robinson as he manned the barricades yesterday.

"Then you get a group who have negative reactions," added his partner, Officer D.L. Randall. "They complain that it's hard times out here and that a man has to make money and all they are trying to do is make a living."

While most residents applaud the blockade, many also note that it has not solved the drug problem. In some cases, the drug dealers have moved indoors or to other parts of town.

"We are aware of the societal limitations of dealing with this kind of problem marijuana sales ," said Jack Davis, a Chapin Street resident. "But for us it's different. We're talking about something that pollutes the street. It would be an overstatement to say the block is a war zone, although it does have some of the characteristics of being under seige. There is always a fear of going out at night because of robberies and gunfights."

"What boggles my mind," said his wife, Marianne Davis, "is how a situation like this can exist in the capital of our nation, which we claim to be the leader of the free world. How can we lead the free world when we can't stop drug dealing right under the eyes of the police?"

The Chapin Street Citizens Association is expected to meet soon with police to discuss these and other questions about area law enforcement. Specifically, the members want to know what landlords can do about people who deal in drugs from apartment buildings.

And there are the drug dealers themselves, whose style has changed for now, though the substance of what they do remains the same.

From the doorway of the Byron Hall apartment building on Chapin Street, a youth discreetly whispers, "Hey, want some'n to smoke?" He ducks back inside a deteriorating, malodorous hallway and explains his tenacity over a din of disco music, drunken laughter and infant cries.

"They can't stop me," the youth says, head bobbing and eyes darting as he scans the streets for customers. "It's like this: I have children. They have needs. I got needs. I needs money."