The girls of summer have spoken, and “Lady Marmalade” is their song. Apologies to soul survivors Destiny’s Child, but the star-studded cover of the ’75 LaBelle smash from the Moulin Rouge soundtrack (Interscope) is the first definitive car-stereo anthem of the ’01 beach season. It looks good on paper and sounds even better over the airwaves: the increasingly captivating Christina Aguilera wails her way through the song’s goofy French chorus (with modest accompaniment from Lil’ Kim, Mya, and Pink) while producers Missy Elliott and Rockwilder conjure a supremely cheesy rock-guitar riff and the coolest cowbell to hit radio since Shania Twain’s “That Don’t Impress Me Much.” It’s enough fun in the sun to melt teen pop’s entire winter of discontent.

Christina’s eagerly awaited sophomore disc won’t be in stores until the end of the summer, but fellow pop thrushes Jessica Simpson and Mandy Moore have new material out just in time to capitalize on the post-“Marmalade” rush. At 20 and 17, respectively, they’re on opposite sides of the class-of-’99 teen-queen age spectrum. So it makes sense that their new albums find them at different stages of the coming-of-age process: cover girl Mandy is sweet and innocent as ever on Mandy Moore (Epic), but Jessica sheds her church-girl trappings once and for all on Irresistible (Columbia), unleashing her inner sex bomb to eye-popping (and sometimes ear-pleasing) effect.

Jessica scored with a couple of dreary ballads from her debut, Sweet Kisses (Columbia), before getting to the good stuff (the sexy summer ’00 smash “I Think I’m in Love with You”), but she gets right to the point on Irresistible. “I know I meant to say no,” sings the avowed virgin right before the first chorus of the title hit, as the beat drops out in anticipation. “But he’s irresistible/Up close and personal/Now inescapable/I can hardly breathe” — and if it’s not quite as irresistible as the recent “Mutt” Lange–produced Corrs track of the same name, it sure is one hell of a tease.

Even more lascivious than Jessica’s musical come-ons are the three glamor shots of her in the CD booklet, starting with the one on the cover where she pouts into the camera and pulls her see-through blouse above her bellybutton. There’s a picture of the Dallas native in something that looks almost like a Cowboys cheerleader outfit, and finally a softcore porn centerfold shot of her in a form-fitting turtleneck sweater and black leather mini-skirt. God Himself would have trouble saying no.

Appearances aside, the rest of Irresistible is less provocative but just as much fun. Jessica orders a noncommittal suitor to be straight with her on the perky “What’s It Gonna Be,” a masterful update of Britney Spears’s “Lucky.” Veteran teen-pop producer Rodney Jerkins (Destiny’s Child, Backstreet Boys) contributes a stellar Stevie Wonder homage, “Imagination.” And Jessica and guest vocalist Marc Anthony sing with undeniable bravura on “There You Were,” saving the disc’s soggiest moment from itself.

Compared with Jessica, Mandy has trouble standing out on Mandy Moore — and not just because she doesn’t show as much skin on the album cover. Teen pop has a tendency to stray into adult contemporary, and Mandy seems particularly susceptible. Her most recent hit, last summer’s “I Wanna Be with You,” was a bit of a snooze, and it’s not a good sign that most of the highlights on her new disc are ballads. The lush vocal harmonies on the chorus of “Saturate Me” are positively majestic; the tender “17” is teen pop at its most introspective. And Mandy’s conscience, unlike Jessica’s, gets the best of her: on “17” she sings, “I’ll save my misbehavior for a little later/’Cause I’m only 17.”

Mandy does manage to resurrect the upbeat charm of her first hit, “Candy,” on the new disc’s lead single, “In My Pocket.” Produced by Latin pop vet Emilio Estefan Jr. (Gloria Estefan’s husband), it’s a creative mix of Eastern melodies and Latin grooves with a dark chorus that might be a little too obtuse for the Radio Disney set. The album is not without its carefree moments, like the spinning “Yo Yo” (“I’m not a yo yo/I’m not a thing you let go”) and the faux psychedelic “Split Chick.” But too often it passes on good times in favor of locked-in-my-bedroom melodrama. For now, Mandy gets by on cuteness alone, but these days girls just wanna have fun — and if she doesn’t join the party soon, she might get left behind.

Mandy Moore signs copies of her new CD this afternoon (June 21) at 5 p.m. at the South Shore Mall Record Town in Braintree. Call (781) 848-9423.