In the social evolution of a new psychological syndrome, there may be no moment more important than the appearance of its first celebrity victims. A star or maybe a fading star "discloses" a "troubling diagnosis" that he or she has "struggled with" in "silence." The star receives warm studio-audience applause and big Hollywood hugs for "bravery," for "just wanting to help others in the same situation." (In the case of rockers and drugs, the evidence of a "struggle" is often kind of thin; more often it looks as if they partied really hard and then slacked off a bit when they turned 50 or 60 or the drummer died.) Meanwhile, as the celeb makes the rounds of the talk shows or "sits down" with People magazine, the syndrome itself moves up in the world, acquiring a new high profile, maybe a catchy acronym and a presumption that it is "far more widespread" than we ever realized.

This is the stage we have now reached with "social anxiety disorder," also called "social phobia" and colloquially known as shyness. The condition had been identified in the D.S.M., the bible of psychiatric diagnosis, as far back as 1980. But until recently, it was thought to be a rare disorder, characterized not only by a distracting nervousness at parties or before giving a speech, say, but also by a powerful desire to avoid such situations altogether. Then in 1999, buoyed by the success of the new psychotropic drugs, the pharmaceutical company SmithKline Beecham began marketing its antidepressant Paxil as a treatment for social phobia. Public awareness campaigns equated the syndrome with an allergy to people. Experts cited alarming new statistics -- around 13 percent of us were socially phobic, for example -- and magazines dished up the requisite alarmist trend stories. A set of traits and behaviors, at least some of which were once regarded as neutral or even desirable, re-emerged as a pathology -- a function of brain chemistry, amenable to and indeed demanding pharmacological manipulation.

Enter the socially anxious celebrities. Donny Osmond was one of the first to come forward with a full-scale confessional. Recently, for some reason, it has been athletes. The English soccer star David Beckham, who is married to a Spice Girl, published a memoir last fall in which he admitted to being painfully shy. And last month, the New Orleans Saints running back Ricky Williams told reporters that his social anxiety disorder had been officially diagnosed and that he is now medicated for it. The syndrome, he said, accounted for his unusual behavior: keeping his helmet on during rookie-year interviews, curling up inside his locker. It was touching, actually, to hear Williams's teammates rally around him. "We're all family," a defensive tackle said. "If one of us hurts, all of us hurt." But it was also a reminder that it is much easier to turn on the spigots of empathy and attention these days when you can cite a diagnosed imbalance in brain chemistry rather than an eccentricity, a character flaw or an economic disadvantage.

In two years, then, social anxiety disorder has picked up all it needs -- a psychotropic drug of choice, an army of advocates, a handful of celebrity sufferers -- to sustain itself as a widely recognized syndrome. And for some people, people truly incapacitated by their fears of others' disapproval, that is a blessing. It will make it easier for them to seek help and perhaps obtain relief.

And yet, there are always costs to medicalizing what is not, essentially, a medical condition. If extremely shy people require a pill, maybe mildly shy people could be improved by one, too. How about a few more outgoing types in the office -- fewer Eeyores, more Tiggers? Advocates of the new diagnosis are forever saying that social phobia is worse than mere shyness, but in practice the line between them is fluid, depending as it does on highly subjective judgments about whether a person's social reticence causes significant "distress." As an article on the subject in a recent issue of American Family Physician acknowledges, social phobia can be tricky to diagnose because "the types of fears and avoidance commonly associated with" it "are, to some degree, experienced by most people." I took the social phobia inventory, a self-administered test offered on the Facts for Health Web site among other places, including Paxil's site, and on one afternoon got the verdict that I was not socially phobic and on the next that I might be and should consult my clinician.

The truth is that shyness is not exactly an objectively measurable condition -- or trait or whatever it is. A generation ago, personality assessments folded it into the general category of introversion and characterized neither introversion nor extroversion as pathological. In surveys taken in the 1970's and again in the 1990's, the percentage of Americans claiming to be shy jumped from 40 to nearly 50 percent, which suggests not some mysterious epidemic of shyness, however you define it, but more likely a shift in social values. Maybe more people feel shy in a culture in which the omnipresent media is so full of the aggressively unshy. Maybe in another generation or so, we'll find ourselves sorely missing the meek and the mild, the stoic and the taciturn among us. Is somebody out there inventing the drug to treat excessive perkiness?