When I attended Arlington's Williamsburg Junior High School in the 1950s, it was new and nestled into a community of luxury homes that belonged to people who had Arrived. John Glenn lived across the street from the school for a while.

Back then, it had seventh, eighth and ninth grades. Today, it has seventh and eighth and is called a middle school.

Williamsburg fed into Washington-Lee, which in my graduating year had the second-highest number of National Merit semifinalists in the nation. Not bad for what was still, in many respects, a sleepy southern town, as evidenced by the fact that W-L did not admit people of color until my junior year and you could not buy liquor in restaurants.

My time there saw the dawn of rock-and-roll, and we ushered it in toward the end of high school with beer smuggled into well-chaperoned parties. I was smoking by then, so I was no Miss Goody-Two-Shoes. But it wasn't until my senior year of high school that I saw beer at a party. And my date that evening saw enough of it that I used the dime I always carried with me to call my brother to come and take me home.

We had fun, but the main thing we children of high achievers wanted to do was get good grades. Our parties were all supervised. Parents might leave us in the recreation room. But then somebody would turn the lights out, and automatically a parent would reappear and so would light. The biggest excitement occurred if a couple got caught necking. Some cool parents were more permissive than others: They'd let us leave the lights off for the last half of the party. There were some parents who let us play spin the bottle. But my recollection is that the lights had to stay on, and the lucky couple had to go into the laundry area. And if they took more than a minute or so, there was much clamoring from the rest of the partygoers to come back out so we could spin the bottle again, and somebody else could get lucky.

Getting lucky meant getting kissed. We did not go all the way in junior high school, and many of us graduated from high school with both our minds and bodies intact. Like girls today, we were petrified of getting pregnant, only more so. There was no birth control pill, abortion wasn't legal, and we knew with every fiber of our being that our parents would kill us if we did become pregnant. Life was blissfully uncomplicated back then. There were rules, and they were unyielding.

A few years ago, when I was researching "The Difference," my book on how girls grow up differently from boys, I reviewed the current research on adolescent sex. I also interviewed extensively my daughter and her two best friends, who were then between the ages of 12 and 15 and had shattering insights into contemporary adolescent life. I came to one overriding conclusion: Parents are blind if they use their own sexual benchmarks to gauge the level of sexual activity of their offspring. Girls are exposed to sexual pressure at shockingly young ages, whether it is sexual harassment or an intense pressure to "put out" that starts in seventh grade. That's when they learn that "third base" is not just a baseball term.

Seventh grade is the year everything shifts. Trusted friends from elementary school become cruel betrayers of the most intimate secrets. Eighth-grade boys turn seventh-grade girls into targets of opportunity. Seventh grade, I believe, is the most dangerous year of a girl's life.

So I was not surprised when I saw the headline in The Washington Post the other day: "Parents Are Alarmed by an Unsettling New Fad in Middle Schools: Oral Sex." Williamsburg was the focal point, but Post reporter Laura Sessions Stepp interviewed health and school officials from across the area and found the same pattern: "Eager to avoid pregnancy and hold on to virginity, an increasing number of teenagers are engaging in oral sex," she wrote.

Williamsburg Principal Margaret McCourt-Dirner had held a meeting with about 25 parents of girls last year and told them that she had information their daughters had been engaging in oral sex at parties during most of the school year. She recommended that the parents get to know each other and that they make sure their daughters are where they say they are going to be.

McCourt-Dirner was later criticized for not also calling in the parents of boys. It's hard to imagine a more volatile, finger-pointing meeting than would have resulted had she called in the boys' parents at the same time. But there was no separate meeting with them, either, and it's not clear whether anyone actually contacted them. Vive the double standard.

Nonetheless, McCourt-Dirner is to be commended for notifying parents who are, in the word of one human sexuality consultant, "clueless." Schools need to enforce an atmosphere in which respect between the sexes is as important as racial and religious respect.

"I thought I would be able to tell the day my daughter became sexually active," one mother told Stepp. "I was dead wrong." Most of us are.

All of the experts I interviewed agreed on one thing: Children are doing dangerous things at younger ages. The rule of thumb I came up with for parents is to consider at what age you experimented with sex, take four years off that and then you've got a realistic shot at knowing when your child is becoming sexually active. You'll also know when your window of opportunity arises to give your teenager the information you want him or her to have. If you start when your teenager is 16, you are four years too late. Very bright kids, from very nice families, hit the sexual fast track in middle school.

Parents can be shocked to their socks, but the most important thing they can do is to help their daughters understand the grail of popularity is not worth their loss of self-respect. And the most important thing they can tell their sons is that hitting on girls is not a sign of manhood. Respecting them is.