It seems fair to say that Daniel Radcliffe has not grown up quite like any other young star before him, and has not turned out like anyone expected.

Certainly his success in playing the title role in the "Harry Potter" film series, which has grossed more than $6.3 billion worldwide, has yielded unparalleled recognition and astronomical wealth for Mr. Radcliffe. He is said to be earning $20 million to $25 million for each of the last two films.

And he is about to leverage the decade he has spent playing the boy wizard and take on the starring role in a stage revival of "How to Succeed in Business Without Really Trying" on Broadway.

"If I can actually do it," Mr. Radcliffe, 21, said of his stage adventure, "having been in one of the biggest franchises ever, then that can end the debate. It is possible. That's what's my mission is."

Mr. Radcliffe does not seem to possess the arrogance or petulance that typically comes with fortune and fame. He is self-aware but un-self-conscious, wide-eyed and fidgety, and quick to portray himself as mundane and geeky.

But when it comes to his career - the eighth and final "Harry Potter" film will be released this summer - Mr. Radcliffe is deeply, preternaturally serious. Explaining why he chose to bid farewell to his beloved character with a 50-year-old all-American satire of the corporate world, he spoke, with an almost religious sincerity, about his need "to prove that a child actor can go on to have a career with longevity."

Mr. Radcliffe made his Broadway debut in a 2008 revival of Peter Shaffer's psychological drama "Equus," which transferred from London. Playing the disturbed youth Alan Strang, a role in which he briefly appeared naked, Mr. Radcliffe drew widespread attention as well as critical praise.

He obtained vocal lessons for a song in that show, and word spread that perhaps he possessed greater ambitions.

In a meeting with Craig Zadan and Neil Meron, two of the producers of "How to Succeed," Mr. Radcliffe said he wasn't sure he was qualified to carry a Broadway musical. And when he was approached separately by the director and choreographer Rob Ashford, Mr. Radcliffe recalled, "I was going: 'O.K., yeah, I'll do dance lessons, fine. But you are swimming against the tide here, Mr. Ashford.'�?

Mr. Zadan had a somewhat different take: "It was his secret desire to do this," he said of the Pulitzer Prize-winning musical about J. Pierrepont Finch, who starts out as a window washer and ends up the chairman of the board.

"I think to a lot of people it's a slightly confusing choice," Mr. Radcliffe said, "but I like that."

Mr. Radcliffe has not sung often and has never danced or spoken with an American accent for any role, and he has already spent months training in these areas.

And he is stepping into the role of Finch at a much younger age than his Broadway predecessors, who were in their early 30s.

At a recent rehearsal of one of the show's rousing numbers, Mr. Radcliffe threw himself into every kick, pivot and strut, and with some assistance flipped from a boardroom table into the arms of waiting cast mates. But there was no mistaking how diminutive the actor, at 165 centimeters tall, looked next to the others, and how his 193-centimeter co-star, John Larroquette could completely eclipse him from view.

Mr. Radcliffe said he hoped the passion he brought would at least temporarily compensate for any perceived shortcomings.

"If you're enthusiastic enough about stuff - even if you're not good at it - your enthusiasm will get you to the point where people allow you to do it enough so that you become good at it," he said.

Momentarily letting down his guard, Mr. Radcliffe confessed that he was anxious about how he would be received in "How to Succeed." He rattled off a rapid list of concerns: "Fear of failure. Fear of mediocrity. Fear of not meeting the goals that I have set myself. Fear of failing in my mission."

He was steadfast, however, in his certainty that he would not be saddened by the release of the final "Potter" movie.

"People have to remember, we are not mourning the death of an actual person," he said. "There is not an appropriate grieving period which I have to observe."

The New York Times