(CNN) -- In the long history of attractive young actors and the girls who scream and stalk them, few can translate that teen adoration into leading man respect.
Leonardo DiCaprio did it. Daniel Radcliffe hopes to do it.
But Corey Haim, Luke Perry, Ralph Macchio, Jason Priestley -- they were all beloved in their time, yet none of them earned solid crossover appeal in the grown-up market. Indeed, "Eight Is Enough's" Willie Aames, once the cute and funny boy girls wished they had next door, can now be found on VH1's "Broke and Famous."
The former heartthrobs can fall far when they attempt to make the leap into the big leagues.
But that doesn't mean Zac Efron can't try.
The "High School Musical" series star, 22, recently turned down the lead role in "HSM" director Kenny Ortega's musical version of "Footloose," craving more serious roles. He did this despite the huge success (and paychecks) the song-and-dance roles of the three "HSM" films have brought Efron, not to mention his star turn in the film version of the musical "Hairspray."
So instead of '80s pop, Efron is starring in Richard "Waking Life" Linklater's indie "Me and Orson Welles," heavy with Shakespeare and an artist's philandering. He once again plays a precocious teen, Richard Samuels, but this time it's as the young lover to Claire Danes' older woman. And there isn't a locker or high school gym in sight.
It's a declarative move, proving Efron meant what he said when he hoped out loud he could one day find himself in a film with Martin Scorsese. It's also quite a risky one.
The key to a smooth transition, said youth talent agent Robin Nassif, is Efron's patience and focus.
"George Clooney was around for a long time before 'ER'; I cast him in 'Facts of Life,' " Nassif recalled as an example. "He had a little guest part on 'Facts of Life,' and he did quite a few failed pilots, quite a few failed series, but when that ['ER'] part came along, that was the part that made him a star. [It was] the part that made people say he could do movies."
Lack of patience aside, there are a multitude of other factors that make one actor the next Johnny Depp and another destined for bit parts -- or no career at all. It could be a case of poor management, or that rude, Hollywood awakening when the once-adorable teen grows up to be just an average adult.
Sometimes, said Lisa May, Nassif's partner in the youth division at Diverse Talent Group, "they don't evolve ... they remain 'the best friend' or they just become a less attractive adult kid. It's really how you grow, how you evolve, what you look like as a finished product."
And then there's the question of actual talent.
"They get themselves trapped into doing that one character, and they have a difficult time transitioning themselves from doing that," said Diane Heery of Heery Casting. "Even while doing a show, [an actor] should be getting coaching from somebody or taking a class; being challenged to be somebody else."
No one is more aware of these hurdles than Efron himself, who has repeatedly mentioned how much he looks up to one of the former teen idols who did make it, DiCaprio, and how closely he's been studying DiCaprio's career.
DiCaprio found a way to go from "Growing Pains" to teen heartthrob in the heady drama "Romeo and Juliet" with another teen star-cum-leading actress, Claire Danes, before headlining one of the highest-grossing films of all time, "Titanic." Efron, on the other hand, is trying to find his way out of the Disney-Nickelodeon box that modern tween TV franchises are built on, and it's not easy.
Casting experts say there are things to be gained from the "star power machine" that is Disney (which produced the "High School Musical" series) and Nickelodeon -- namely, jobs -- but admit there are also drawbacks.
The slew of teen-marketed television series "build a whole mystique around a certain actor in order to sell those projects, [and] that's why the actors get pigeonholed -- that's how their producer is selling that product. You have to search for other things so people don't just see one side of you," Heery said.
While there's no formula for bursting through the teen-star ceiling, trying to "gently [push] the boundaries of perception should be the goal," said Megan Larche of Larche Casting, who works exclusively with young actors.
"Leo, Claire and Jodie [Foster] -- if you look at the trajectory of their careers, they have always taken interesting projects that challenged them and us as [an] audience. Their unwillingness to be defined by any particular role has allowed us as the public to love them as actors first, characters second."
Efron's role in "Me and Oscar Welles" may not be all that different from past forays in film -- in the film he's still 17 -- but it is a detour from his usual fare. And Efron does have a few things in his corner -- the first being a rabid fan base.
"He has fans that just put [him] on a pedestal," said Meredith Fine, director of the youth division at Coast to Coast Talent, an agency that represents Abigail Breslin, among others. "And he does have the adult audience, because adults took their kids to see "High School Musical," and "17 Again" appealed to an adult audience, and he was adorable in that."
Adorable, "je nais se quois" -- whatever you call it, Efron's got it. If he didn't, "High School" wouldn't have been what it was, Fine said.
In addition, she added, the guy can act.
"And as he starts to show us more," Fine said, "we'll see it."