It lay across our driveway like a crumpled trophy, 10 feet of steel split in the middle with hoop, net and backboard resting at the end in almost graceful symmetry.

It's not easy to fold a basketball pole in half, but teen-age boys playing monkey can do it effortlessly.

And they did: at our 16-year-old son's unauthorized party for 300 kids the night before we came home from a recent trip.

The crumpled basketball pole on the ground became my invitation to look more closely into the world of teen-age parties -- a world where more than 100 partygoers is not unheard of, where alcohol always appears, where some degree of "trashing" (as the kids call it) frequently occurs. It's a world where police are often called in as the last resort by neighbors, parents and the kids themselves when things get out of control.

Our son's party was for the purpose of showcasing his band, The Mix, and developing an audience to buy the band's album-in-progress.

Our son went to extraordinary lengths to secure our home: He blocked the driveway entrance with a car, hired three teen "bouncers" to see that no one got in without paying a dollar for entertainment, locked all doors to the house except those to the basement and family room, moved all furniture and plants out of those rooms to safe quarters, roped off the rest of the house with heavy extension cords, covered the pond in the backyard with boards, put up signs out front showing exactly where to meet in the back, and used his band's microphone to control and finally disperse the crowd.

But we wondered: What kind of party does a kid envision that he would possibly go to such extremes to protect the property?

A party like the one in Bethesda last fall for 350 teen-agers, where kids ground raw eggs into the carpet, smashed all the glassware in the kitchen, turned over the refrigerator, kicked the doors in and stole all the jewelry belonging to the mother of the party-giver;

Or the one in Gaithersburg this winter where the night before a basketball game kids from rival schools started fighting each other. Police broke it up and were at the game the next day following threats of violence;

Or the one in Arlington, where telephones were stolen and holes punched throughout the house;

Or the one in Potomac recently where a boy climbed up on the roof over the gutters and smashed a large window with a bottle, while another jumped all over the Ping-Pong table in the basement, smashing it to smithereens.

A closer look at teen parties reveals the following profile:

All kinds of kids attend: top students, top athletes and the lowliest on the teen-age social totem pole, the square kids, the with-it kids and those in-between.

There is alcohol at every party. At some, kids bring their own; at others, the teen-ager provides a keg, charging by the cup. Loud rock music plays continuously in the background, whether from a band or a radio, uniting the kids and promoting their feeling of togetherness.

There is an instantaneous network of communication that should be the envy of NATO: simply mentioning "party" to a few key teens is all that's needed. Within a few hours, word has spread not only to hundreds of students in a school but to several other schools as well. Maps may appear spontaneously, as in the case of the Bethesda party.

As a result of this incredible network, kids show up who don't even know the host. Says one 11th grade boy: "You really have to work at finding out whose house you're in."

Often the "trashers" are strangers to the host. They've been described as "professional" crashers who go from party to party wreaking havoc in anonymity. But I was also told that many kids at the Bethesda party knew the trashers, who were sports figures at a local high school.

And the boy at whose party the Ping-Pong table was smashed saw the kid at school afterwards.

A few parties have parental approval. One boy told of a recent gathering where parents even provided kegs of beer. "It was for graduation," he says, ignoring that the legal drinking age in Maryland is 21, not 18. Most, however, are unauthorized and thus unchaperoned -- usually given when parents are out of town, much as in the movie "Risky Business," which captures the essence of the surge of freedom teens can feel with parents away. "I would never have gotten permission from my mother," says a boy whose party was notable because the crowd hit 500. "People still talk about my party," he says, adding that he looks forward to being able to say in college: "I had the most kids." His party also will be remembered for the way it ended. "I got scared when I heard windows break," he says. "I went to my neighbors and said, 'Let's call the police.' They already had."

The police, in fact, are very involved in the teen party scene. "We treat each party call seriously," says Lt. Douglas McFee of the Montgomery County police, Rockville station, which sent officers to "bust" nine parties on the last three weekends.

"Kids think they can control it, but the sheer numbers get out of hand," reports Capt. Mike Blasher of the Bethesda station.

"It is never simply just a party. It impacts the entire neighborhood," says Blasher. "You are dealing with traffic problems, speeding, the question of driving under the influence of alcohol or even drugs."

Police say they treat parties with strategies similar to riot control, and have even used tear gas to disperse hostile crowds. "Usually kids will disperse quickly and pleasantly, but there have been hostile confrontations," says Blasher.

"Police don't want to be the enemies of kids," he continues. "But we've had kids spit on us, curse us, throw bottles at us, let air out of our tires. As individuals they're nice kids, but in a crowd, behavior can change."

"Breaking up these parties can take hours, dozens of police cars, and be as hard as breaking up family fights."

Everyone has theories explaining teen parties: the influence of TV and movies like "Animal House," the social status of alcohol as well as its forbidden nature, kids' access to cars, the lack of small-town community watchdogs, parents' own self-involvement and refusal to set limits on their children.

Psychiatrist and psychoanalyst Stephen Kwass sees the teen party scene as a response to particular stages in adolescent development. "There's a normal, if temporary turning away from parents, their influence, values and social goals," he says. "One of the things that happens is kids redirect feelings from their parents to their peer group. The group comes to serve as the source of their primary relationships, replacing parents.

"The group then is the source of approval or disapproval," says Kwass, who is a faculty member of the Baltimore-Washington Institute for Psychoanalysis. "The group presses its members to conform to the same standards, the same clothes, language, music. Insofar as members don't conform, this brings into question the validity of the group itself. The purpose of peer pressure is actually to validate the group."

He continues: "Getting together at large parties to appreciate the same music, speak the same way, yell the same way, serves to validate all the members involved.

"What better way to feel good about yourself than to be valued by 400 people?" says Kwass.

As for the "trashers," Kwass suggests that the "violence comes from within, from the youngsters struggling the hardest with difficult, angry and conflicting feelings about their parents. Trashing may be an assertion of lack of concern for parents, for what they represent, for what represents them.

"If trashers are popular and charismatic group leaders, the other kids may follow or at least admire their behavior," he adds.

Meanwhile, the party season gets into full swing this weekend, as schools start letting out.

Our son's band has sold more than 100 albums.

The pole and hoop still lie out front of our house. Either we'll install a new pole or bring in a welder to fix the old.

Whichever the decision, that dollar-a-head cover charge is going to pay for it. Myra Patner is a writer who lives in Potomac.