You're walking at twilight near the Marine Barracks at Eighth and I streets SE, when through the late summer air comes the gung-ho chant of a Marine company on double-time march.

Down the street they come, running in formation, uniformly clad in olive drab fatigues and combat boots, singing out the cadence in regulation heigh-di-ho style.

But wait! They're only four feet tall!

"Company HALT!" shouts their adult leader. "Atten-HUT!"

"Young Marines, Sir!" shout the Munchkin marchers, snapping to alert.

"I can't HEAR you."

"YOUNG MARINES, SIR!"

"That's better," sighs Marine Cpl. Alex Duff, with the enduring exasperation of the eternal drill instructor. "But you still sound like a bunch of little girls."

In the front row, Chantelle Palmer, 10, sneaks a grin from beneath her fatigue cap at her mother on the sidelines.

"Or little mice," Duff says, catching her glance.

It happens every Wednesday night. From 5:30 to 7:30 p.m. about two to three dozen 8- to 14-year-olds scramble to the historic brick barracks to march and drill some order into their streetwise young lives.

They come from the apartments of Anacostia and the streets of Shaw and the barracks' neighborhood projects beside the Southeast Freeway to a volunteer youth program run by a handful of off-duty Marines. They come to be instructed in courtesy, neatness and leadership, disciplined with push-ups, and shouted at by instructors who demand obedience, untiring effort and above all, responsibility and self-respect. It's boot camp every Wednesday.

Yet so many flock to the barracks each week that the program has quadrupled to nearly 100 children in the past year. Parents of Young Marines say their children work harder, do better in school and show a new sense of pride. They themselves enlist skeptical neighbors.

"My son listens to me more now," says Panya Washington, a single parent from Southeast whose 8-year-old, Telly, has been a Young Marine four months. "He even folds his clothes. They teach him 'Yes, ma'am' and 'No, ma'am'. Manners. Discipline. Kids need that foundation for life. Everything ain't selling drugs and going to the go-go."

"They teach him to respect himself, love his country and believe he can do anything," says Maureen Pease, who drove from Annapolis last Wednesday to enlist her 8-year-old as the only white child in a program of inner-city blacks. "He was a Young Marine in New Bedford, Mass. It made him more grown up. It taught him to accept responsibility."

Like the Boy Scouts, which since its founding in 1910 has taught generations of Americans the survival skills of a rural age, the Young Marines espouse character building and high ideals. But unlike the Scouts, their first focus is mastery of self.

"We don't involve them with firearms or anything like that," says Marian Reintges in the Young Marines headquarters in Ada, Mich. "It's like the Boy Scouts but there's more emphasis on close-order drill. We believe that teaches discipline, and we look on discipline not as a punishment but as something young people need in life to regulate themselves."

At the Marine Barracks in Washington, the program is about five years old, but according to Gunnery Sgt. P.A. Gross, until last year rarely numbered more than 20 youngsters out of a nationwide total of 1,600.

Gross, who began directing the program 14 months ago, compiled its first history and service records and began pushing for members.

"We went on a recruiting drive," says Gross. "We had the kids wear their uniforms to school and that brought a lot of inquiries. They've been coming in ever since."

Uniforms, however, remain a problem. It costs about $40 to outfit a Young Marine--no small sum to most of their families. Individual Marine Corps members sponsor some children and outfit them, but others drill without the uniforms.

The biggest recruiting draw may be the barracks itself, where John Philip Sousa wrote "Stars and Stripes Forever" and where Friday night dress parades unleash a Kiplingesque spectacle of ritual and dash among the gentrified town houses and sweltering projects of the near Southeast.

Wide-eyed children rubberneck through the gate at the red coats and silver instruments of the Drum and Bugle Corps, and gawk at the sentries resplendent in dress blues. The thunder of Sousa marches echoes for blocks.

"Maybe 80 percent of these kids come from the neighborhood here in Southeast," says Gross, career counselor for the barracks. "At least 60 percent of those come from single-parent families. Kids like that don't have much structure in their lives. They get that here."

Rose Palmer, who brings her daughter from Anacostia for the program, agrees. "The children get a father image--somebody to look up to," she says. "And we know they'll discipline the kids without hurting them."

"See, it's like this," says William Hemphill, a lanky 15-year-old who has been in the program seven months. "I'm a PFC now but I can get a promotion. Depending on the stuff I learn. Then I'm a corporal, see. And I'm over all the PFCs."

What do they learn?

Marco Felder, 8, a Young Marine four weeks: "My faces. I learned all my faces."

Faces?

"You know, like left face, right face . . . "

On a recent sweltering night at Eighth and I, Corine Carroll stood before Sousa Hall, hands on hips, eyeing with some satisfaction the band of orderly marching children who had been trading punches and hilarity moments before.

A massive woman in a cotton house dress, she has been the Young Marines' unofficial community counselor since the program's inception.

"I'm supposed to make sure they're not too hard on the kids," she says. "Actually, I make sure they're not too easy."

Before her Cpl. Duff scowled ferociously as he ordered a squirming 12-year-old to "10 and 10"--10 push-ups and 10 sit-ups--for wearing a belt buckle with insufficient gleam.

Duff, 21, an Appalachian-born bugler in the Drum and Bugle Corps, tugged blouses and squared caps on his miniature charges as they stood at attention, eager for approval.

"I don't know what I'm going to do with you men," he says. "You're going to have to do better than this."

"What I try to tell them," he says, momentarily out of earshot of his charges, "is never to quit: that the only way to lose and be a loser is to give up. I was one of 10 kids from a place called Long Hollow in Virginia. We had no electricity, no running water. Most of these kids have a jump up on me. I want them to know what they can become."

Suddenly, at his side, stood David Cleveland, 8, lip atremble beneath the visor of his fatigue cap.

"Cleveland, why have they sent you over here?" Duff demands.

"Because I wouldn't march."

"Why wouldn't you march."

"I was afraid."

"Why were you afraid?"

" 'Cause they might laugh at me."

"Listen, Cleveland," Duff says, crouching beside the small figure. "You can't let that worry you. It's not what they think that matters, it's what YOU think. People are going to laugh at you from time to time all your life. It happens to all of us when we make mistakes. But there's nothing wrong with making a mistake as long as you're trying your best. You got that?"

"Yes, sir."

"All right, get back there and march."