In the late 1960s, the pharmaceutical company Sandoz introduced a new tranquilizer called Serentil, which was aimed at people who felt nervous in social situations. Serentil, according to the ad, could ease the "anxiety that comes from not fitting in," a feeling that practically every person on the planet has undoubtedly experienced. But Sandoz was prevented from tapping this potentially enormous market by the U.S. Food and Drug Administration, which forced the company to withdraw the drug and issue a statement to the effect that Serentil was useful only for "certain disease states" and was not intended for use in everyday, anxiety-provoking situations.

Thirty years after Serentil flopped, pharmaceutical giant GlaxoSmithKline launched its own ad campaign for Paxil, an antidepressant that could also be used to treat "social phobia," a debilitating form of shyness that psychiatrists had recently identified as a diagnosable ailment. The company sent out press releases describing the disease, provided reporters with lists of sufferers willing to speak publicly about their condition, and papered bus shelters with posters and the slogan "Imagine Being Allergic to People." The promotional campaign hardly mentioned the drug, let alone the manufacturer, notes author Carl Elliott, because pharmaceutical companies have learned the lesson of Serentil: If they want to sell a drug that will "take the edge off some sharply uncomfortable aspect of American social life," as Elliott puts it, they first need to persuade Americans that their discomfort is due to a bona fide medical problem. "SmithKline does not need to sell Paxil," he writes. "What they need to sell is social phobia."

That, in a nutshell, is the pattern of America's obsession with enhancement technology: drugs and procedures that are supposed to make us happier, calmer, sexier. In a word, better. "Doctors begin using a new drug or surgical procedure that looks as much like cosmetic intervention . . . as a proper medical treatment," Elliott writes. The technology triggers a heated debate; "Brave New World is invoked." But in the end, the technology is accepted as a part of ordinary American life. Today dozens of drugs, including Paxil, Viagra and Prozac, straddle the fuzzy line between enhancement and medical treatment, and millions of Americans blithely undergo surgical procedures for everything from pudgy thighs to excessive blushing.

The acceptance of enhancement has been aided, says Elliott, by the American devotion to the self, which allows us to see everything from which brand of jeans we wear to cosmetic surgery as just another way to find and express the inner person. The quest for the true self can take extreme forms. Elliott recounts stories from an underground group of Americans who are not only sexually attracted to amputees; they also want to have one of their own limbs or digits amputated because, in the words of one sufferer, "I don't feel like myself with this whole body."

Nut cases? Maybe, but it's possible to see their desire as merely a strange new twist on the American pursuit of self-fulfillment. Fifty years ago, it would have seemed equally inconceivable that thousands of perfectly healthy people would willingly undergo a major operation each year to change their sex -- or that one day such surgery would be considered a perfectly reasonable treatment to repair the psychic well-being of a person who is born one sex but who cannot feel complete unless he or she becomes the other. "We tend to see ourselves as the managers of life projects," writes Elliott, managers who must constantly search for ways to make our lives better, richer, more psychologically healthy. But this notion of life as a project leads to a degree of moral uncertainty, and to the belief that we are solely responsible for the outcome of our endeavors. To that end, we have drafted medicine and technology into the service of having good lives rather than being good people.

Better Than Well is a superbly crafted book. Lucidly written, often funny, it offers a penetrating look at our self-obsessed, over-medicalized, enhancement-addicted society. But Elliott goes further than this. Better Than Well also lays the groundwork for thinking about the difficult and contentious issues surrounding gene therapy and human genetic engineering. One day, parents will be able to practice the ultimate form of enhancement, endowing their offspring with desirable genes.

Bioethicists often draw a bright line between so-called therapeutic technologies, which are deemed good and moral, and enhancement technologies, which are not. Thus genetic therapy that can cure a disease such as cystic fibrosis is good, but genetic engineering to give a child blue eyes or greater intelligence is bad. The problem with this construction, as Elliott makes clear, is that the distinction between treatment and enhancement gets a little blurry in a society that has become adept at turning many aspects of ordinary existence into medical problems. Is it enhancement to give growth hormone to increase the stature of boys who will achieve only below-average height? Or therapy to protect their egos? And once biotechnologists find the genes for stature, will we want to ensure that all our sons are above average and all our daughters do not grow too tall?

The ability to alter the genes in embryos is coming soon to a culture that sees self-expression and identity as commodities that can be purchased. The implication of this eloquent, disturbing book is that it will be very difficult to stop genetic enhancement, or even slow it down.