About a decade after a woman gives birth to a girl, she begins to know exponentially and unequivocally less about fashion than her daughter. I’m not talking about (what are for me) the classics; I’ve got a DVF wrap dress, a half-dozen Betsey Johnsons, and at 30 paces can peg the best polyester hostess gown in Goodwill. I mean what’s going on now: When did acid-washed jeans become “sand-blasted,” and what’s up with all the denim, anyway? Is Lenny Kravitz to blame for oversize accessories? Are we on the 67th or 76th resurrection of the peasant blouse? How would I know? Like realizing I haven’t read the last Amis book when the next is being reviewed, at a certain point I simply stopped trying to keep apace. I chalk up my befuddlement, and my 12-year-old daughter’s concurrent awareness, to some shark-like sartorial survival gene that needs to keep moving if it’s to stay alive. While Tafv likes wearing my Emilio Pucci nightgowns (which I inherited from my mother), she’ll also shoot me looks of abject terror when I try on old outfits I think still work.

“No, Mama, you can’t!” she’ll shriek, tossing the blouse with the ruched sleeves back in the closet.

“But I wore that when I was pregnant with you . . .”

“Mama!”

Embarrassment factor for Tafv if I wear the blouse: 704. Luckily, I still understand humiliation. And so, while it may be true that I was stranded in the fashion undertow two years ago, I also unwittingly did something brilliant, which was go online and order Delia’s (www.delias.com).

For those unfamiliar with Delia’s, it’s a catalog of hip-huggers and bikinis, prom dresses and accessories, draped on teenage models who, with their navel rings and tank tops imprinted with dangling cherries, wear expressions poised between “I love sleepovers!” and “I just did the gym teacher.” The opportunity to dress as naughty girls (as opposed to actually being naughty) has proved enormously appealing to ‘tweens, and Delia’s exerts a pull not unlike J. Crew, the defining yuppie catalog perused less for clothes than for clues as to how to look as though you, well, shop at J. Crew, whether you plan to get into a canoe with a Labrador or not.

The Delia’s home invasion (a new catalog arrives about every three weeks) has proved to be all things to all two of us: Tafv can choose outfits at breakfast or in bed; I never have to set foot in a mall (a trip that for me ranks right up there with standing in line at the DMV in August); and, a boon I really couldn’t have foreseen, because she was 10 at the time, and tiny: As soon as Tafv tires of or outgrows the clothes, she gives them to me.

“Your mom is so hip,” her friends tell her, staring at my feet, at the black-leather-with-tan-stitching sneakers Tafv wore only once before I absconded with them (and which several acquaintances have been mistaken for Prada’s riff on bowling shoes). I think she likes to hear this because she knows that any credit for good taste is strictly hers, and because she never has to be embarrassed about what I wear.

Which means I say yes to about everything Tafv circles in the Delia’s catalog, nudging her toward skirts with room for hips (which she does not have) and halters with built-in bras (which she does not need). Am I being practical/economical? Fending off middle age/death? I make Tafv a grilled cheese sandwich and slap a few recent issues of Delia’s on the kitchen table.

How old do you think people should be to wear Delia’s?

“You mean, the limit?” she asks, turning the pages, it seems to me, in a bid to avoid eye contact. “They can be in the 20s, but over 20s, they can’t wear them, Mother.”

Then how come you let me wear yours?

“Because you can look good in them. The other mamas can’t.”

That’s very sweet. Does Delia’s carry the current styles?

“Well, there are different styles,” she says slowly, in a try-to-follow-along-here tone. “Delia’s will have themes. Sometimes it’s clothes like Britney’s, which I don’t really like. This issue’s kind of . . . leather/lace. Shakira kind of clothes.”

The model on the cover sort of looks like Shakira. I guess they do that on purpose.

“That is Shakira. See, ‘Shakira,’” she says, running her finger over bright-blue type that reads shakira! and, next to it, in Tafv’s girlish script, Shakira, complete with a penned-in arrow pointing at, um, Shakira.

“I don’t like that,” Tafv says, frowning at a girl in a floppy hat, a fringed suede belt and a gauzy floral top. “What is this style called?”

That would be hippie.

“Yeah, hippie, but in a motorcycle-gang kind of way.”

Honey, do you think there will come a time when I say, “Hey, the Delia’s catalog came!” and you’ll think, God, she’s so uncool . . .

Tafv laughs. “Probably,” she says. “Abercrombie & Fitch is taking over. The style now is comfy but hip and sporty, like pants with a stripe down the side, and a little tank top with a #4 on it.”

Both of which she currently wears, having borrowed them from a friend. I look at the little top, and wonder if it will fit.