This is disco with a different beat. From a solid bank of wall posters, Peter Frampton, John Travolta and the Bee Gees smile benignly. Flashing orange, blue and yellow spotlights illuminate dancers caught up in the rhythms of The Fight, The Squirm and The Rock. Girlfriends huddle over the merits of Electric Sox in the Disco Shoppe. A 16-year-old reapplies Black Orchid lipstick in a mirrored corner dance area.Two 13-year-olds belly up to the bar for Strawberry Smashes. Others play Surf Champ pinball in a side room. Littlefeet, the first area disco strictly for kids, is in full swing.

This particular Friday might, 200 youngsters circulate inside the former Hot Shoppe in Fairfax County south of Seven Corners. They are between 12 and 18 years old and paid $3 to dance from 7 to 1. Between dances, they lean elbows on the bar, just like grownups, and order Cokes or the same slushy fruit fantasies served at adult discos, but without liquor. It's a restaurant, too, although the only hot food served comes out of a microwave oven. The menu consists of hamburgers, hot dogs and chips, all standard teen fare. Thirst-quenchers include Coco Cabana, a rumless pina colada, and Banana Boogie, a daiquiri without spirits. Nothing costs more than $1. And it's better than hanging out at the local 7-Eleven.

"About time they opened something for teenagers," says 15-year-old Khalid Traish during a dance break.

Owner Tony Newton says those sentiments express exactly why he put $40,000 into a test market for a teen disco. Newton, Bill Paley and Fred Moore, principals in the Gandy Dancer restaurant, have a year's lease before this building is torn down for a high-rise. They are now scouting a location between Seven Corners and the Beltway for another Littlefeet, says Newton.

"We know we've got a market. Kids buy this stuff - T-shirts, records. Parents work to give kids more than they had themselves," he says. One parent, Gigi Connally of Arlington, came to "look the place over before I let my 16-year-old in here."

Connally, like most parents, is worried about alcohol, pot and supervision at Little-feet.

Tom Patterson, the 21-year-old "second DJ and a little bit of everything else," is making sure "no one is getting into trouble in the parking lot."

He's one of 14 adults and teenagers hired to supervise Littlefeet. Newton doesn't want to call them chaperones. Kids don't attend school dances, says Newton, because of stares from parents, teachers and chaperones. But Connally complains that she can't tell the supervisors from the kids because they are "all in civilian clothes."

No drugs or alcohol are allowed on the premises. Smoking is not permitted inside the building, and if kids want to go outside, they have to pay 25 cents to return.

"Our whole purpose is to create an atmosphere," says Newton.

The asmosphere is your basic disco environment: A darkened, mirrored room holds red-and-black leather banquettes, a powerful sound system and scattered tables and chairs. One main dance floor is flanked by two small corner ones. Overhead, a revolving silver ball casts shards of light around the room. Kids are treated like adults in these surroundings.

Sometimes problems erupt, caused by school rivalries or individual competition. Then the individuals involved are handled with maturity, says Newton.

"We gently pick them up and walk them to the door and talk with them about what we've got here," he says.

What they've got is the hottest new twist in the nation's disco craze.

On opening night at Littlefeet, 1,500 teenagers passed through the doors, according to Newton; the maximum allowed at one time is 300 persons. After the opening, Littlefeet shut down to revamp a fire door and Newton says his phone rang off the hook with calls from parents anxious to know a reopening date.

Parents are welcome, too, but only in the restaurant; they are not allowed to dance.

Lou Glasener sits at the curved restaurant counter waiting for five 13- to 18-year-old girls he brought here from Montgomery County. He used to take this group to Intermission restaurant at White Flint Mall, but Intermission stopped its policy of Sunday afternoon disco for kids. Anyway, Glasener says, he likes Littlefeet better.

"Kids couldn't wear jeans at Intermission. They dressed rich," says Glasener. Tonight almost everybody is wearing jeans, and tube tops or T-shirts.

"Kids come here to have a good time, not to be Disco Danny or Disco King," says disco jockey Rocky La Liberte - or Dr. Rock, as he prefers to be called.

"There's no disco like a teen disco. It's very challenging. People come up and say 'Play disco' or 'Play rock.' Nobody dances to white music. They all seem to want to dance to black music or soul disco. People want to hear Van Haylen or Sister Sledge. I play a ratio of five-to-one disco to rock and ten-to-one fast to slow. Slow dancing is just so they can cool off, and gets the guys and gals a little closer together," he says.

The 16-year-old disco jockey plays records from a glass-enclosed booth resembling an airport tower. Wearing his great grandfather's beaver top hat with silver trim, he puts on a Rod Stewart record.

"Is this Friday night?" he yells.

"Yeah, yeah, yeah," youngsters scream as they head for the dance floor.

Dr. Rock plans dance contests at Littlefeet in the next few weeks. Prizes will be record albums and concert tickets. Newton also has changes in store for Littlefeet: He plans to inaugurate a buffet and disco on Sunday for the entire family.

"After church," says Newton.

Right now, the kids seem to like it just the way it is.

"I adore it, it's the greatest. Everybody's talking about it in school," says 13-year-old. Pam Deutsch from Glasgow Junior High School in Alexandria.

Some teenagers are there because parents think it's a good idea.

"My mom thinks it's a great thing to do because we're always bored," says Pam's friend Blair.

Some youngsters says if they weren't here they would be home watching television. And not everyone comes to dance.

"We get to listen to music, that's what we like," says 17-year-old Cindy.

Music, dancing, pinballs or just plain socializing, it's now available for kids in their own special place. Why not?

As one Sunday morning television host used to say, "Kids are people, too." CAPTION: Pictures 1 and 2, no caption, AP