Just when parents of middle-schoolers start to feel comfortable leaving their kids alone after school, they probably shouldn't.

And so Americans--in astonishingly high proportions--are telling Democratic and GOP pollsters that they want more and better after-school care.

"There is a silent revolution going on," says Adriana de Kanter, special adviser to the Department of Education. "People are particularly concerned about middle school kids. It's like apple pie and motherhood." As many as eight out of 10 polled say they would pay additional taxes to improve the quantity and quality of after-school care, she adds.

Armed with such public support, national education officials meet today with youth advocates, policymakers and social scientists at the National Academy of Sciences to discuss how best to fill the after-school hours. Their efforts are spurred in part by federal allocations for after-school care that have risen from $1 million in 1997 to $600 million proposed for next year.

Numerous studies have shown that between the hours of 3 and 8 p.m., teenagers are most likely to smoke, drink, use drugs, engage in sexual activity and commit crimes. Proportionately, very few kids do any of these things, but de Kanter and other experts suspect that the desire for more programming is based largely on Americans' fear that their own kids might. This anxiety is fanned by two facts: In the majority of families, both parents now work outside the home, and kids who experiment recklessly today do so at younger ages than kids in previous generations. Parents also know how hard young adolescents are to please; if 10-to-15-year-olds don't like a certain activity, they're outta there. After-school advocates also would like parents to realize, however, that activities do more than keep kids safe. When run by adults who understand the needs and challenges of young adolescents, programs can help all youngsters, enabling them to identify and sharpen specific talents and skills, build friendships with other kids their age and connect to caring adults. Early adolescence is probably the most fragile transition in most kids' lives, the experts say; the places they go to after school help determine how well they make it through.

The Boys & Girls Clubs of America, whose 3 million participants include about 1.5 million young adolescents, surveyed alumni this year on the impact club membership has had in their lives. Pollster Lou Harris reported the findings at a breakfast in Washington, saying that even he, a veteran of polling surveys, was astonished at the high number of respondents who said that club participation had boosted their self-esteem and their grades. Half the respondents said it literally "saved their lives."

The best after-school programs share certain characteristics, according to several experts. These programs:

* Give participants "voice and choice." Preteens and teenagers need to help design their own programs and come up with meaningful choices of things to do. Their radar immediately picks up whether their ideas are being taken seriously. If they are not, many will leave. Collaboration is critical because many kids don't get much time in their daily lives with adults they trust and can talk to.

Alternatives should include opportunities to pursue activities that they already enjoy and pursuits that they would like to try for the first time. "They need to be able to make mistakes in a safe, sheltered environment," says Jacquelynne Eccles, chair of the National Academy workshop and professor of psychology at the University of Michigan. One of their choices should be community service, she says, for kids this age are eager to make a contribution and have an impact.

* Offer kids unstructured, private space to hang out away from adults, although adults are in the building to assist when needed. "Kids this age need to be able to talk together privately," says Linda Sisson, executive director of the National School-Age Care Alliance, an accrediting organization. "They need to discuss their day and the teachers and other adults who give them grief. A lot of programs think their task is to see and hear the children at all times. This is not a match."

* Encourage kids' natural inclination to do things in groups. Kids who hook up with other kids to perform a play, create a mural or put on a photo exhibition start to identify themselves with those groups as opposed to others that might not be so healthy. "They will say things like, we are kids who are good at music, or who do drama," says Eccles.

* Incorporate learning techniques into most activities. The more kids this age use their newly developing skills in critical thinking, the better thinkers they will become.

The experts are quick to add one caveat to the need for structured learning: Don't call it that. Call it cheerleading or dance or, for the overall program, something generic--such as "Panthers After Hours," Langston Hughes Middle School's program in Reston. The last thing young adolescents want to do after school is more school.

Panthers After Hours

It isn't easy to touch your toes in midair when you have 13-year-old arms and legs, at least with any pretense of grace. But Cyrena Jenkins obviously doesn't know this as she spread-eagles three feet off the ground to the envious stares of 13 other cheerleaders in training at Langston Hughes Middle School in Reston.

"Wow, did you see her?" asks schoolmate Blair Kirby, 12. Minutes later, tall and fair-skinned Blair positions herself next to Cyrena, tall and dark-skinned, and together they lift tiny Viviana Garcia into the air.

Later Blair and Cyrena admit that if it weren't for cheerleading, they likely wouldn't know each other. And if it weren't for cheerleading, they'd probably both be at home talking on the telephone or watching television. Such confessions are music to the ears of Shauna Cole, teen director at the Reston Community Center. Cole coordinates cheerleading and 20 other activities that make up an after-school program run by the center and Langston Hughes.

On Tuesdays and Thursdays, more than 60 kids assemble for selections from a menu that includes horseback riding, salsa dancing and a program titled "How to DJ." Cole recalls that in the summer of 1997, she assembled 10 middle school students and asked them for their dream activities.

"One kid said, 'Study hall?'

" 'Study hall!' I responded. 'You're telling me you want study hall?' And he said, 'Well, that's what you do after school, isn't it?' So I said, 'Think about anything,' and they started getting wild."

The after-school program, called Panthers After Hours, has experienced very few disciplinary problems, Cole says. "Once kids this age figure out what they want to do, they just take off. I don't have to worry about them."

Still, 60-plus students is not a tremendous amount for a school of more than 900 students. School and community center officials market the program like crazy in local newspapers and fliers, but say lots of Reston kids are already involved in the community's highly organized sports program. Other youths have parents who don't realize the value of engaging kids in extracurricular activities, according to Hughes Principal Prentice A. Christian Jr.

"I tell parents all the time that kids who are involved in meaningful activities have consistently better grades," he says.

Latin American Youth Center

Christian Cruz spends his afternoons feeling his way around a photography darkroom. It is a metaphor for his early years, before he started coming to the Latin American Youth Center--crazy days of trouble at home and the confusion that comes with having nine older brothers and sisters.

On his first days at the center, he would arrive on his bike with red marks on his neck from street fights. He was a tough sixth-grader who ran with a crew and was afraid of no one. A year later, the marks are gone and his photography instructor, Marie Moll, trusts him enough to leave him in charge, saying, "Just close the door and turn out the lights when you're done." He flashes her a big grin.

"In school, they don't really care what you do," he says, running his hand through a thick and shiny brown mane. "Here they do. Bive [Alvin Alvarado, a youth worker] tells me, 'Hey man, stay out of fightin'.' I do."

Bive, Marie, Sonya, Chico--the names float effortlessly through Christian's conversation. Listen to other youngsters here and you'll hear other first names. Judy Posado and Erica Cruz praise Willette [Coleman], a drama instructor who coached them in lead roles in a recent play, "Violence Is Stupid." Judy and Erica also like each other. Judy, a two-year center member, recently taught newcomer Erica how to play pool. They pronounce themselves best friends.

Of all the gifts kids receive from the center, the most precious may be the gift of trust, says Lori Kaplan, the center's executive director. Many of the kids, Latino, Asian American and African American, come from families struggling with near poverty, marital problems and unresponsive bureaucracies. Trust is hard to come by in their corners of the world. But they can find it with the center staff, half of whom are former center kids, and with each other.

Now in its 32nd year, the center serves about 400 kids a day either at its headquarters--a tall brick building at Columbia Road and 14th Street Northwest--or at sister sites in various schools. Originally started for older teens, "we are doing more and more with the middle school age group," Kaplan says.

Christian is an unpaid salesman. "My friends say, 'Where do you go every day?' and I say, 'To the center.' They say, 'Where did you learn to do these pictures?' and I say, 'At the center. You should stop by.' "

CAPTION: Participants in Langston Hughes Middle School's after-school program in Reston, called "Panthers After Hours."

CAPTION: Viviana Garcia tries to keep her balance during cheerleading drills. From left to right, Blair Kirby, 12, coach Seana O'Doherty and Cyrena Jenkins, 13, hold her up.

CAPTION: Judy Posada, 13, has been coming to the center after school for two years.