ccording to the official Popular Baby Names Web site, the name we are considering for our daughter, to be born later this summer, was in the Top 200 for her sex last year. It was less popular than Molly but more so than Abby. This has me worried. It seems perched at a precarious point from which it could, without warning, rocket into overuse. Witness Chloe, which has shot from 184 to 24 since 1991. Call out the name in your local Gymboree, and four little heads will whip around.

Popular Baby Names, which is operated by the Social Security Administration, ranks the 1,000 most common boys' and girls' names since 1900 (www.ssa.gov/OACT/babynames/). You can also look up a specific name and track its status over time (an activity that, I warn you, is an Internet addict's sinkhole). The site, started seven years ago, was initially the side project of a government actuary named Michael Shackleford. Michael reigned as the No. 1 boys' name for 35 years beginning in 1964, after about a decade of duking it out with David and Robert. It was unseated by Jacob in 1999.

Shackleford grew up, with no small amount of bitterness, in a multiple-Michael world. He hoped that by publishing the list, parents-to-be would see that his name (and other common names) were shopworn and choose something more original. (Shackleford, incidentally, quit the Social Security Administration in 2000 and moved to Las Vegas, where he has become a gambling consultant known as the Wizard of Odds. His own children are named Melanie, No. 88, and Aidan, No. 63.)

Perennials like Michael or Sarah are not, to my mind, the nub of the issue. They don't explain why so many people seeking more adventurous names seem to hit upon the same ones. Why did I recently receive birth announcements from three couples who had never met, who lived as distant from one another as Maine, Minnesota and California, yet who had all named their sons Leo? How to account for the sudden spate of Natalies?

I am not so smug as to think myself immune to first-name zeitgeist. A few years ago, I developed a sudden affection for Julia, which now hovers at 31, and then for Hannah, which is No. 3. Although I have never personally met a Madison (2), I have watched friends seduced by the seeming novelty of Alyssa (12), Olivia (10) and Dylan (24 among boys), only to discover that their children are destined to spend life with the initials of their last names appended to their first.

While my husband doesn't seem concerned -- at least judged by the excessive eye rolling when I bring up another contender -- I've trawled the Social Security site for clues to the potential future of ''our'' name. I've sifted through message boards on pregnancy sites to see if it has cropped up among other moms-to-be. I've checked a site that polls users to determine a name's image based on continuums of ambition, attractiveness and athleticism. I've even looked on the Kabalarian Philosophy site, which, using a supposed mathematical principle, analyzes the ''power'' hidden in more than 500,000 names. None of that, however, explained what I really want to know: how a particular name becomes popular and whether it's inevitable, like it or not, that my husband and I will choose the next Kayla (19).

amela Redmond Satran and Linda Rosenkrantz have built their empire on the backs of people like me. Their eight books, including the classic ''Beyond Jennifer & Jason, Madison & Montana,'' have sold more than a million copies; a new volume, the pared-down and pointedly titled ''Cool Names,'' will be published next month. Like ''Jennifer & Jason,'' it is part advice manual, part pop sociology text. Avoiding the deadly (and useless) dictionary format, it divides names into sections. There's the safe Hot Cool (Polly, Harry); the famous Cool Cool (Charlize, Keanu); the retro Pre-Cool Cool (Beata, Lazarus); and the New Cool, which encompasses, among other things, constellations (Elara, Orion). The express purpose is to help jittery parents-to-be separate current favorites from what's about to break big from what the daring among them can pioneer.

The duo read the baby-name tea leaves of preschool class lists, maternity wards and birth announcements. They also consult the Social Security site, though Satran warns of a critical glitch: it doesn't combine alternative spellings. In 1998, for instance, Kaitlyn was way down at 36. But if you totted up the Katelyns, Caitlins, Caitlyns, Kaitlins, Katelynns, Katlyns, Kaitlynns, Katelins, Caitlynns, Katlins, Katlynns and Kaytlyns, that name would have easily bested the No. 1-ranked Emily. Like any kind of forecasting, though, from predicting cargo pants to recognizing that we're about to have an orange moment, picking the next Grace (15) is as much art as science. ''We look at all the lists,'' Satran says. ''We look at movie stars' names and what they're naming their children. We look at names that cut across several trends at once. But after that, it's just instinct.''

Satran and Rosenkrantz have a pretty solid record of prognosticating, particularly on groups of names. They sounded the alarm on the use of places (Paris, Sierra, Asia) as first names in 1988, years before that trend slid from mainstream to cliche. A friend named her daughter London, Satran remembers, which caught her attention. A short time later, she heard about a baby boy named after a Pennsylvania town. She then met a Holland and heard about a Dakota. Those encounters dovetailed with an uptick of androgynous names for girls. By the time Alec Baldwin and Kim Basinger named their daughter Ireland, Satran and Rosenkrantz knew that place names were firmly on the map.

Names weren't always subject to fashion. About half of all boys in Raleigh Colony were named John, Thomas or William, and more than half of newborn girls in the Massachusetts Bay Colony were named Mary, Elizabeth or Sarah. Even in the 20th century, John, William, James and Robert were, in some combination, the top three names for boys for more than 50 years. Among girls, Mary held on to No. 1 for 46 years, when it was supplanted for six years by Linda, fought its way back for another nine, then succumbed to the juggernaut of Lisa.

These days, even a popular name isn't especially prevalent: though the name was ranked fourth, there were only about 16,300 Emmas born last year. Sell-by dates are shorter too, at least for girls. Only three of today's Top 10 names (Sarah, Samantha and Ashley) survived since 1990.

With boys -- well, there's Michael. Parents continue to be more conventional with their sons, more conscious of tradition and generational continuity. Girls' names are more likely to be chosen for style and beauty. That makes them both more interesting to track and more vulnerable to sounding passe, the human equivalent of bragging about your new pashmina.

The Harvard sociologist Stanley Lieberson first bumped up against the fashion quotient of names in the 1960's. Believing they were bucking convention, he and his wife named their eldest daughter Rebecca, only to discover a few years later that she was part of a pack. How had that happened? The marketplace, after all, has no interest in what we name our children; no corporation profits if you choose Kaylee over Megan. That makes names one of the rare measures of collective taste.

Lieberson, the author of ''A Matter of Taste: How Names, Fashions and Culture Change,'' insists that names generally rise and fall independent of larger cultural or historical events. Consider the resurgence of Biblical names. ''They came back like gangbusters in the late 20th century,'' Lieberson says. ''There was speculation that it was related to a resurgence of religion. But people who use Old Testament names are, if anything, less religious in their behavior than those who don't. It's just fashion.''

Naming styles, Lieberson says, are usually variations on what came before, moving forward predictably, the way lapels get wider and wider until they reach a peak and switch direction. He calls this ''the ratchet effect.'' Take Old Testament names. In 1916, Ruth, for no obvious reason, was the only one to crack the Top 20 for girls. After it crested, it was replaced by Judith in 1940, then Deborah in 1950. By the late 1980's, there were three Old Testament names among the top slots: Rachel, Sarah and Rebecca. Now it's Hannah, Abigail and Sarah, with Leah (90 and holding) as the only potential replacement. Perhaps after a hundred years, girls' Biblical names have ratcheted as far as they can go.

Sometimes, Lieberson explains, rather than a concept, it's just a sound that catches hold: the ''a'' at the end of girls' names (Emma, Hannah, Mia, Anna), or the hard ''k'' at the beginning (Kylie, Kaylee, Caitlin, Courtney). That breakthrough sound undulates outward, in a kind of jazz riff, gradually mutating. So the ''djeh'' sound in Jennifer begat Jenna and Jessica, but Jennifer also begat Heather and Amber, which share its suffix. (Before Jennifer, the only commonly used ''er'' name was Esther, which was never a favorite.) Those names went on to spawn waves of their own. African-American parents, who are more likely than other groups to invent names for their daughters -- again, less often for their sons -- recently became enamored with ''meek'': Jameeka, Camika, Mikayla. (Remember the legendary three ''meeks'' of the Tennessee Lady Vols basketball team -- Tamika Catchings, Chamique Holdsclaw, Semeka Randall?)

But why does ''a'' or ''djeh'' or ''meek'' appeal in the first place? Why not the ''th'' in Ethel and Thelma (or Ruth!) or the final ''s'' in Gladys and Lois? That's harder to explain. ''My speculation would be that a sound like the final 'a,' which did not used to be particularly popular, probably broke through as a variation on some existing name,'' Lieberson says, ''and then it developed its own life.''

That's not to say that external forces are irrelevant. Race clearly influences naming. So does class, especially among whites. Lieberson found that highly educated mothers are more likely to give daughters names that connote strength (Elizabeth or Catherine as opposed to Tiffany or Crystal). Yet, when it comes to boys, the trend reverses, with the more bookish moms going for Julian over Chuck.

That's the problem with the Popular Baby Names site: with no nuance, no dissection by demographic, it can get you only so far. For instance, Satran and Rosenkrantz recently polled upscale nursery schools in Manhattan and Berkeley, Calif. Among that crowd, Charlottes (206) and Rubys (210) ran rampant, but it was a desert for Savannahs (40).

After a couple of hours of my relentless quizzing, Satran (whose own children are named Rory, Joseph and Owen) suggested that some people become a tad obsessed by their quest for originality. While it may evoke a particular theoretical profile (Bambi, anyone?), there is no definitive evidence that a name affects an individual child's popularity, mental health or achievement level. ''There are people who want to sell the idea that your name is your destiny,'' Satran says. ''Names aren't your destiny any more than your shoes are.'' She pauses, then adds, ''Well, O.K., maybe your shoes are your destiny.''

On the other hand, when she recently advised a friend that Maya was becoming overexposed, it made no difference. Sometimes people fall in love with a name and don't want to believe it's played out. Or they're comforted by something that's a touch more common -- not everyone wants to be a trendsetter, not even those who say they do.

''There's this ideal,'' Satran says, ''not just in names but other things that have to do with style, that you should make a personal statement. But the fact is that most people are not that adventurous. They say they want individual style but they pick their furniture at Pottery Barn. So if you tell them you're going to name your child Matilda, they'll say, 'That's awful.' But if you say Sophia or Lily or any of the names that I'm totally sick of, they'll say, 'That's such a beautiful name.' ''

Even pros like Satran and Rosenkrantz are occasionally blindsided by a name, as when Trinity leapfrogged to 74 after the release of ''The Matrix.'' Popular culture is an oft-cited launching pad for naming fads -- soap operas most famously (Kayla, Hunter, Caleb and Ashley all zoomed upward after star turns on daytime dramas). Still, the effect is not as direct as it may seem. Buffy, despite a fanatic cult devotion to the vampire slayer, has not breached the Top 1,000 (although Willow has been climbing modestly since 1998). Aaliyah surged after the singer's death, but Diana barely budged after the Princess of Wales died.

A closer look finds that Trinity was already on the upswing, from 951 in 1993 to 555 five years later. ''Riding the curve,'' as Lieberson calls it, is often the true explanation behind a pop-name phenomenon. A name (or a sound sequence) is in the air, albeit marginally so; because of that, it's used for a character or happens to be that of a high-profile performer (like Jada, 78). That, in turn, catapults the name forward, seemingly out of nowhere.

Bringing us back to the improbable popularity of Madison: it first hit the Top 1,000 in the 1980's and it was, unlike Trinity, probably a pure media event originating in the film ''Splash.'' Recall that, while struggling to choose a name, Daryl Hannah's mermaid strolls onto a certain Manhattan street, et voila.

Still, Madison? No. 2? How in the name of good taste did that happen? Satran points to a confluence of trends: Madison came along at a time when place names and surnames (McKenzie, Morgan) as first names were hot, as well as the related androgynous names for girls (Taylor, Sydney) and the Ralph Lauren, faux horsey-set names (Peyton, Kendall). Then there's Lieberson's phonetic wave theory. In this case, Madeline (56) may have begun to grow tired while Madison sounded just a little fresher. So when Madison finally sinks, who will replace her?

On a hunch, I typed another New York place name into the Popular Baby Names site: Brooklyn. Sure enough, it has vaulted from 755 to 155 since 1991. Then I tried expanding in a different direction on the sound chain from Madeline and discovered that Adeline was inching up as well. Given those trends, it would not be as random as it would appear if, a few years from now, Adelaide and Portland, two seemingly unrelated names, were both in the Top 10.

Now I was getting somewhere. A few nights later, I saw a film that took place around 1900, a mother lode of contemporary names for both sexes. One character was Annabelle. That sounded jaunty. I liked it. But what was its appeal? Then I recalled the current popularity of the Isabella/Isabel/Isabelle chain (14, 84, 112) not to mention Anna (20) and Ella (92). Lovely names all, but they've been done. That made me suspicious. As it turned out, Annabelle was rising with a bullet (from 984 to 330 in seven years, while Annabella went from 963 to 722 in just one). The following week I spied it monogrammed on a sleeping bag in the Pottery Barn Kids catalog. Annabelle was off my list.

Michael aside, overuse usually spells the end of a name, at least for a while. Names also lose luster when they become tied to a particular era. If you really want to ensure your baby girl will be unique among her peers, name her Barbara, Nancy, Karen or Susan. Or Peggy. Those sound like the names of middle-aged women because -- guess what? -- they are.

But names are often resurrected when the generation that bears them dies out. Although our mothers may joke that the play group made up of Max, Rose, Sam and Sophie sounds like the roster of a convalescent home, contemporary parents find those names charming. Doubtless, today's Brittany will name her daughter Delores.

Or maybe she'll call her Remember. Satran claims that the next big trend will be word names. Colors, for example (she just heard of a baby Cerulean), or words that resonate with the parents' values or professions like Integrity or Story. ''There's been a street-level thing happening for a while with names like Destiny and Genesis,'' she says. ''They weren't mainstream, but they were there. The tipping point came when Christie Brinkley, who is very visible, named her daughter Sailor because she and her husband liked to sail. Parents are increasingly looking for names that are different and also looking for names with personal meaning. Word names are a natural place to go. It's virgin territory. Our grandchildren will have names we don't even think of as names now.''

Satran expects to see a fad in heroes' last names as first names (Monet, Koufax) as well as futuristic or Asian-sounding names borrowed from video games (Vyce, Ajuki). Among African-American parents, she says, the coming thing will be idiosyncratic punctuation accelerated by the singer India.Arie and the singer Brandy, who recently named her daughter Sy'rai.

Which brings me back to the name we are considering for our daughter. We're not, as it turns out, willing to saddle her with something as outre as Minerva. And Zazie or Tallulah are just trying too hard. Our name, as the experts would predict, is a sideways hop rather than a radical leap from names that have recently been stylish. So yes, it could take off. Still, it's a little softer, a little more free-spirited than its precursors, not the sort of name you'd imagine for a future Wall Street gunner. But that suits me fine: I ditched the East Coast 15 years ago for the sunny iconoclasm of Northern California and a life that has become far less conventional than I once imagined. I want my daughter's name, and, I suppose, her life, to reflect that.

I hesitantly asked Satran's opinion, realizing that, like the mother of Maya, I might refuse to heed it. Had we accidentally picked the next Zoe? ''Nope,'' she said. ''I think you're safe.''

So what is it? I can only respond with Satran's parting piece of advice: ''Don't tell anyone the name before the baby is born. Do you really need to know about the girl with that name someone hated in fourth grade?''

She's right. Besides, I don't want to start a trend.