Leonardo DiCaprio has seemed a reluctant movie star ever since he broke out in the 1997 blockbuster "Titanic." Perhaps he listened to what Robert De Niro told him during the filming of 1993's "This Boy's Life": "Overexposure can kill you," the veteran actor said. "Handle it right, and you'll have a great career as an actor." Like Jodie Foster and Warren Beatty, who believe that it's better to promise films of quality and preserve a little mystery, DiCaprio has not chased a high celebrity profile. But after this year, with "The Departed" and "Blood Diamond," two awards-season movies released back to back, DiCaprio will have to work harder than ever to avoid the spotlight. In "Titanic's" wake, the actor didn't go out of his way to make small films, though "The Beach" and "The Man in the Iron Mask" ended up that way. For the most part, DiCaprio's choices have been commercially astute. And hitching his fate for the past five years to auteur Martin Scorsese and producer Graham King, on "Gangs of New York," "The Aviator" and "Departed," was a good move. While DiCaprio learned a lot working with the master -- the director opened up his film library to the actor -- he didn't quite carry "Gangs"; Daniel Day Lewis dominated that movie. And as the youthful Howard Hughes in "Aviator," even though he earned his second Oscar nomination, DiCaprio still seemed a tad lightweight. But King insists: "To me, he was a man coming out of 'Aviator.' In every scene you saw an actor like Clark Gable or Steve McQueen."

Like many performers who started young (remember TV's "Growing Pains?"), DiCaprio has been confined by something that even his prodigious gift couldn't transcend: his youth. As strong as he was in everything from 1994's "What's Eating Gilbert Grape," in which he earned his first Oscar nomination, to 1996's "Romeo + Juliet" and "Marvin's Room," DiCaprio was limited by his age. Every male actor is a boy until he becomes a man -- especially in America, which tends to celebrate boyish men. It's hard to believe that Johnny Depp, Brad Pitt, Nicolas Cage, Tom Cruise, Sean Penn and Keanu Reeves are all past 40 and well into their primes. DiCaprio is a full decade younger.

Since they met on "Gangs," says King, DiCaprio knew where he wanted to go. "He was mature about it. He performed like a complete pro. He had no issues," he says. "He's thorough when he decides to do a movie; we spend a lot of time talking about the character and the script. I've seen him mature as a person over the last five to six years."

Suddenly, this fall, DiCaprio has turned the corner. He's now 31. Almost 6 feet tall, he has lost his baby fat and grown more facial hair and muscle. Finally, it seems, DiCaprio is willing to own and accept his stardom, to wear it with ease. His third teaming with Scorsese has yielded what Robert Duvall in "Network" would call "a hit, a big-titted hit!"

"Departed," a Boston gangster picture, is holding strong at the boxoffice, grossing more than $79 million in three weeks. While DiCaprio is part of an acting ensemble led by Jack Nicholson and Matt Damon, he's the one who pops. Playing a cop uneasy with his undercover assignment as a mole within the mob, he is the emotional heart of the movie.

This was not part of Warner Bros. Pictures' original game plan. "Departed" was an unpretentious commercial picture slated for an early fall release, with the same studio's "Blood Diamond" slated for 2007. But "Diamond's" director, Edward Zwick ("The Last Samurai"), delivered his South African adventure on such a swift timetable that it caught up with the slower-paced Scorsese film and landed a coveted December 15 release date in Oscar primetime. "Diamond" is a big expensive drama with a heartfelt political message, just the kind of movie that needs the extra boost of an Oscar campaign.

In that film, DiCaprio is front and center in an anti-hero role. He's a ruthless South African diamond smuggler who enlists perky journalist Jennifer Connelly to help him find the missing son of South African farmer Djimon Hounsou -- as well as his buried giant diamond. Along the way, Connelly and Hounsou's characters both help DiCaprio's damaged treasure hunter find his conscience. It's DiCaprio's movie all the way, thick Afrikaner accent and all, and Warners is pushing him for a best actor nomination.

There's just one problem: The studio's "Departed" has become such a hit with critics and audiences that the one movie Scorsese and DiCaprio had no intention of campaigning for has become a serious Oscar contender as well. This leaves the studio scrambling to take care of the needs of all its players.

The studio now will mount Oscar campaigns for both "Departed," which already is a commercial success and doesn't need an Oscar push to attract audiences, and "Diamond," which needs all the help it can get. DiCaprio is facing the happy dilemma of handling two possibly Oscar-worthy performances. Warners says it will campaign for DiCaprio in the best actor category for "Diamond," a movie whose political agenda he cares about deeply.

At this point, according to his PR rep Ken Sunshine, DiCaprio will join his "Departed" brothers in the supporting actor category, which will pit him against Nicholson and Damon in a hugely competitive race along with likely contenders Hounsou, Adam Beach ("Flags of Our Fathers"), Eddie Murphy ("Dreamgirls"), Jackie Earle Haley ("Little Children"), James McAvoy ("The Last King of Scotland"), Michael Sheen ("The Queen") and Alan Arkin ("Little Miss Sunshine").

This leaves the best actor race relatively sparse, with "Scotland's" Forest Whitaker going against Peter O'Toole ("Venus") and Will Smith ("The Pursuit of Happyness"). Even if Warners positions him as a supporting player, Nicholson is enough of a senior star to move into that category as Anthony Hopkins did for "The Silence of the Lambs." And if "Departed" really takes off as a best picture contender -- and if "Diamond" doesn't -- then DiCaprio too could be promoted from supporting actor consideration for the Scorsese movie into a best actor aspirant for that movie as well.

Whatever awards they ultimately earn, both films reveal DiCaprio's ability to play layered characters who are both good and bad, capable of violence and tenderness, anger and fear. He's now in great shape to be a grown-up movie star like Jimmy Stewart, Henry Fonda or Cary Grant -- actors who knew how to play the Hollywood studio game while keeping their true natures in reserve as they grew into maturity and increasing gravitas. All three had enough edge to keep moviegoers guessing about whether they would reveal themselves as villains or heroes.

DiCaprio could next portray Theodore Roosevelt for Scorsese, or take on a thriller like Robert Ludlum's "The Chancellor Manuscript." Regardless, it's exciting to watch him coming into full command of his gifts. "Departed" and "Diamond" mark just the beginning of the best stage of this star's life.