The Jonas Brothers -- Kevin, left, Joe and Nick, right -- pose with actress/singer Miley Cyrus in Los Angeles, Calif. (Kevin Winter/Getty Images)

Judging by a joke at the end of their ubiquitous new video, even the Jonas Brothers are a little worried they’re growing up too fast. The clip for Burnin’ Up, the lead single from the band’s recently released third album, A Little Bit Longer, contains an amusing series of vignettes from prospective Jonas movie and TV projects. While 20-year-old Kevin Jonas appears in a Kung Fu knockoff starring David Carradine, 15-year-old Nick gets to be a suave, 007-like secret agent. As for 18-year-old Joe, he’s more scared than stoked about the possibility of starring in a Miami Vice parody called Hot Tropic. As he explains to his bandmates in a worried tone of voice, “I can’t grow a moustache.”

Joe needn’t be so perturbed – we live in a world in which no Jonas brother should feel pressured to look like Tom Selleck. But can things stay like this for long?

The members of the current generation of Disney-bred teen performers are making tentative steps toward adulthood. Miley Cyrus, the 15-year-old daughter of country hunk Billy Ray Cyrus and the star of the Disney series Hannah Montana, weathered controversy earlier this year when salacious photos of her appeared in Vanity Fair. High School Musical’s Vanessa Hudgens was the object of similar consternation when provocative pictures of her leaked onto the internet in 2007. Hudgens’ career might have been hurt by the attention, but it’ll take more than questionable photos to slow down the Miley juggernaut. Her new album, Breakout, debuted at No. 1 in the U.S. and Canada in late July and is sure to stay near the top spot for a long time to come.

In the months between the publication of the Vanity Fair photos and Breakout’s release, there was much speculation about whether Cyrus’s new album — her second under her own name and the first without the Hannah Montana banner — would reflect a newly adult sensibility. Beyond the title track’s complaints about school and the somewhat mystifying attempt in Wake Up America to raise ecological awareness (“Global warming, going green, I don’t know what all this means”), nothing on the new disc warrants a parental advisory sticker. Designed to shore up Cyrus’s fan base, Breakout features a proficient blend of lite, slumber-party-ready rockers and anthemic ballads that would compel concertgoers to flick their Bics — if they were old enough to smoke.

Singer Miley Cyrus performs onstage during Nickelodeon's 2008 Kid's Choice Awards in Los Angeles, Calif. (Kevin Winter/Getty Images)

Cyrus’s team of writers and producers includes ex-Go Go's drummer Gina Schock and Matthew Wilder, the one-hit wonder (1983’s Break My Stride) who produced No Doubt’s breakthrough, Tragic Kingdom. They have tweaked the formula enough that Miley can keep pace with her maturing audience but also gain some credence outside it. Simple Song and the B-52s-like Fly on the Wall do not reveal Cyrus to be a brilliant new talent, but nor are they the straight-up singalongs of her Hannah Montana discs. Cyrus is clearly looking to make a transition from tween fame to the regular kind, a jump that has eluded stars of the under-13 set like JoJo and Aaron Carter.

Indeed, one of the most striking aspects of the Hannah Montana phenomenon is that it escaped most grown-ups’ attention for so long. When a 3-D concert movie starring Cyrus and the Jonas Brothers set box-office records in February, the news created far less of a stir than those Vanity Fair photos. Even the High School Musical franchise seems curiously under-exposed despite spawning several of the decade’s best-selling music discs and DVDs and contributing dramatically to Disney’s total revenues.

As young stars get more and more attention outside their target demo, they often feel compelled to cater to newer, more grown-up audiences. Compare (if you dare) the first couple albums by the Backstreet Boys and *NSYNC — hear how the predominant sound of the two biggest boy bands of the ’90s shifted from generic, Euro-centric dance-pop to slicker strains of modern R&B. Or consider how Avril Lavigne adopted a more “mature” style (i.e., lugubrious ballads with piano and strings) on her 2004 sophomore disc, Under My Skin, only to make a calculated retreat to bratty punk-pop after her second album met with relatively lacklustre sales. Hilary Duff, Cyrus’s immediate teen queen predecessor, is likely having a similar rethink after the tartier, Kylie-like electro-pop of her 2007 disc, Dignity, got a less than dignified response from fans.

Though Cyrus’s new disc only makes a tentative move toward a Duff- or Kelly Clarkson-style makeover, the Jonas Brothers, her regular touring mates, have made a more confident effort to expand their appeal. Hell, listeners of '70s power-pop groups like Cheap Trick and the Raspberries may be surprised at the slickness and ingenuity of the best tracks on A Little Bit Longer, which seems destined to become one of the year’s biggest sellers.

Joe Jonas of the Jonas Brothers performs during the Burning Up Tour at the Molson Amphitheatre on July 4, 2008 in Toronto. (Malcolm Taylor/Getty Images)

Largely penned by the brothers themselves, Burnin’ Up, Lovebug, One Man Show and Tonight are the very chewiest of bubblegum rock, thanks to buoyant melodies and a surprisingly crunchy guitar sound. John Fields’ clean-but-not-too-clean production ensures that the songs will be equally appealing to programmers at Radio Disney (a network that averages over five million listeners weekly) and stations more apt to play OneRepublic, the Killers or Fall Out Boy — none of whom have made an album that’s anywhere near as consistently engaging as A Little Bit Longer.

Though the view of romantic love espoused in the lyrics is as tame as you might expect from a trio of well-bred Christian lads saving themselves for marriage, some songs have bite. The object of their contempt in Video Girl is difficult to discern — is it an extra on a video set, a deluded fan or a star like Nick Jonas’s girlfriend, one Miss Miley Cyrus? Lines like “They’re all the same, they all want the money/ They’re all insane, they all live for fame, honey” seem to anticipate an all-out assault on the bitch queen that is celebrity. Perhaps the Jonas Brothers could vent their collective spleen on an upcoming concept album.

Of course, by that time, the boys may very well have been consigned to the same bin from which Hanson has been trying to escape for the last decade. Given that both Cyrus and the Jonas Brothers will likely reach their commercial peaks as recording artists this summer, they will want to avert the burnout factor that has hobbled the careers of just about every one-time teen star (except Justin Timberlake). Maybe a good moustache is just the ticket.

Jason Anderson is a writer based in Toronto.