So after a series of medical consultations, the Carters (all these names have been changed at the families' request) put Sharon on lupron, a hormone that slams the brakes on puberty--only to see their happy little girl go into terrible mood swings. "I had a child acting like she was in menopause," says Carter. The parents decided to stop the treatment, and by age 9, Sharon had full-blown breasts and was getting her period.

Laura Stover took her daughter Karen to a specialist when the girl began growing pubic hair at age 5. The doctor put Karen through a battery of blood tests to rule out ovarian tumors (which can force glands to churn out puberty-triggering hormones). But there was no apparent medical problem, and by age 8, Karen had full pubic growth. "We didn't allow her to go to any slumber parties," says Stover. "Or to change bathing suits in front of other children."

Cecilia Morton, in Santa Maria, Calif., has not one but two daughters who developed early. Clara, now 13, started sprouting breasts and pubic hair when she was 8 and began menstruating a year later, at summer camp. Says her mother: "It was scary and embarrassing because the girls in her cabin didn't have their periods yet." Then Clara's little sister Susan, a kindergartner, began developing at the same time. Although Susan's tests were normal, Morton put her on hormone treatments. "We already see how men look at Clara," she says. "If my younger one didn't have the medication, I can't even imagine the problems we'd be having."

If these were isolated cases, they might be chalked up to statistical flukes. But it seems as if everywhere you turn these days--outside schools, on soccer fields, at the mall--there are more and more elementary schoolgirls whose bodies look like they belong in high school and more and more middle schoolers who look like college coeds. "Young girls [in the 5-to-10-year-old range] with breasts or pubic hair--we encounter this every day we're in clinic," says Dr. Michael Freemark, chief of pediatric endocrinology at Duke University Medical Center in Durham, N.C.

It's as if an entire generation of girls had been put on hormonal fast-forward: shooting up, filling out, growing like Alice munching on the wrong side of the mushroom--and towering Mutt and Jeff-like over a generation of boys who seem, next to the girls, to be getting smaller every year (see box).

What's going on? Is it something in the water? That's a possibility. Scientists think it may be linked to obesity, though they've also proposed a witches' brew of other explanations, from chemicals in the environment to hormones in cow's milk and beef. But the truth is that all anyone knows for certain is that the signs of sexual development in girls are appearing at ever younger ages. Among Caucasian girls today, 1 in every 7 starts to develop breasts or pubic hair by age 8. Among African Americans, for reasons nobody quite understands, the figure is nearly 1 out of every 2.

Even more troubling than the physical changes is the potential psychological effect of premature sexual development on children who should be reading fairy tales, not fending off wolves. The fear, among parents and professionals alike, is that young girls who look like teenagers will be under intense pressure to act like teenagers. Childhood is short enough as it is, with kids bombarded from every direction by sexually explicit movies, rock lyrics, MTV videos and racy fashions. If young girls' bodies push them into adulthood before their hearts and minds are ready, what will be forever lost?

The danger, as authors Whitney Roban and Michael Conn pointed out in a report for the Girls Scouts of America called Girls Speak Out, is that the stages of childhood development--cognitive, physical and emotional--have got out of synch. Roban and Conn call this "developmental compression" and pepper their study with poignant quotes from girls struggling to cope with pressures they are ill equipped to handle. "Boys," complains a fourth-grader in their report, "are gaga over girls with breasts."

In retrospect, pediatricians and psychologists say, there have been hints for the past decade or so that something strange was going on. But it wasn't until 1997 that anyone put her finger on it. That's when Marcia Herman-Giddens, now an adjunct professor at the University of North Carolina School of Public Health, published her famous paper in the journal Pediatrics. Herman-Giddens noticed in her clinical work that more and more young girls were coming in with breasts and pubic hair. Intrigued, she launched a major study of 17,000 girls to get a statistical handle on the problem. >>MORE