Sweet Sixteen : Chelsea Clinton is growing up--and somehow, she’s doing most of it out of the limelight. The ungainly girl is now a poised teenager. And don’t tell anyone, but she’s dating.

In her best-selling book, Hillary Rodham Clinton describes the night she and her husband began role-playing exercises designed to prepare their child for a world of hostile politics. Chelsea was 6.

As her father pretended to be a politician viciously castigating Bill Clinton, Chelsea began to cry. But the parents continued the exercise for hours until the little girl “gradually gained mastery over her emotions and some insight into the situations that might arise.”

The indoctrination has continued ever since, with Hillary Clinton never quite certain of her only child’s capacity to withstand the glare of public scrutiny.

“Each time she went out into the world I ached, afraid of what or whom she might encounter,” writes Hillary Clinton in “It Takes a Village, and Other Lessons Children Teach Us” (Simon & Schuster).

The end result of this effort to at once toughen and shelter a little girl cannot be known with certainty. But it was a confidant Chelsea Victoria Clinton who appeared as a kind of political debutante at her mother’s side during the annual State of the Union speech, poised and dignified in a navy blue tailored suit.

Gone were the braces, the riotous hair, the physical ungainliness of girlhood painfully evident when her father took office and she was just 12. For Chelsea, whose Sweet 16 birthday was Tuesday, the waning phases of adolescence are at hand.

“She certainly understands about turning 16 and all the sort of trappings it brings,” says first lady spokesman Neel Lattimore. “It is an exciting time for her.”

It also may mark a gradual, if still limited, period of emergence.

The high school junior’s appearance at the State of the Union speech was, after all, her idea: She sought permission to attend, even calling the White House office seeking a ticket, to bolster her studies in American history.

When Chelsea accompanied her mother on a widely covered trip to Asia last year, it was seen by some as a kind of “coming-out party.” She figures prominently in her mom’s book. And Hillary Clinton recently revealed a secret about Chelsea to Regis and Kathie Lee: “She dates, but don’t tell anybody I told you that.”

While modest, such exposure is surprising given her parents’ severe strictures on media coverage of their only child. If her father wins reelection this year, Chelsea could spend her entire adolescence in the White House, yet she has been less commented upon, photographed and chronicled than any other presidential offspring in contemporary history.

Susan Ford Bales, one of the last teenagers to inhabit the White House, remembers breaking up with a boyfriend and later reading about it in the newspaper. “I would also read in the paper about boys I had dated who in fact I had not dated,” she says.

Not so with Chelsea.

“There are places where Bill and I draw the line,” Hillary Clinton writes. “We have actively shielded Chelsea from the press, for example, believing that children deserve their childhood and cannot have it in the public limelight. It isn’t fair to let them be defined by the media before they have the chance to define themselves.”

As a result, says UPI reporter Helen Thomas, dean of the White House press corps: “We have not laid a glove on Chelsea.”

Only glimpses into the personality and character of the first child--whose name was reportedly taken from the song, “Chelsea Morning” by Joni Mitchell--have managed to eke out:

Chelsea likes to poke fun at her dad when he’s doing something “not cool or appropriate” and sees her mom as overprotective.

She skipped third grade, loves science and history, prefers Chicken McNuggets to hamburgers and hot dogs, and is reportedly a sci-fi nut.

She wears Birkenstocks and passed on piercing her ears at age 13; has been assisted with her math homework by none other than economist Alan Blinder, former Fed vice-chairman; and she enjoys playing pinochle with her parents.

She nettled her dad by giving up team sports like soccer and softball for ballet, and has performed three straight years in “The Nutcracker” at the Washington School of Ballet, where she regularly attends classes.

Last year, according to media reports, Chelsea impressed Pakistani Prime Minister Benazir Bhutto with her knowledge of Islamic history and the Koran, and was photographed riding an elephant in Nepal’s royal Chitwan National Park.

Her parents joke about the nervousness of new young escorts.

“We have seen more speechless boys,” Hillary Clinton says. And they talk with pride of their daughter’s social conscience, self-discipline, strong grasp of reality and “big heart.”

Observers see the Clintons’ efforts at shoe-horning a normal childhood into the bewildering environs of the White House as perhaps their most complete success.

“It seems like everything they’ve done with regard to their parenting behavior is great,” says Charles Figley, a family scholar at Florida State University who studies the children of politicians and celebrities.

Certainly this wasn’t anticipated.

“The eyes of the world will be watching,” USA Today proclaimed in 1993. “Chelsea Clinton’s private life will be anything but private.”

Somehow, it didn’t quite turn out that way. Press coverage, what little there was, has shrunk. Chelsea was mentioned in 1,721 stories in major newspapers in 1993, but only 694 last year. The coverage in major magazines fell from 132 stories the first year to 36 in 1995.

Evan Thomas, Washington bureau chief for Newsweek, theorizes that there may be some compensating factor at work, perhaps because the media have so aggressively covered each parent.

“We’ve never assigned a story about her,” he says. “She seems to be a reasonably normal teenage girl struggling through the rite of adolescent passage, but not in any noticeable, particularly outstanding way. So we just leave her alone.”

The same was hardly true of Susan Ford, who was 17 when her father was sworn in, or even of Amy Carter, who was 13 when her dad left office and was the subject of a media flap when Jimmy Carter acknowledged that he had discussed nuclear proliferation with her.

With the exception of some editorial grumbling about the Clintons’ decision to enroll Chelsea in a private Washington school, Sidwell Friends (tuition: $13,020), coverage of her has been relegated to blurbs:

* CBS spots her attending a taping of the soap opera “As the World Turns” in New York.

* Family Circle magazine chronicles her 14th birthday celebration, where 40 boys and girls descend on the White House for pizza in the State Dining Room and a showing of “Reality Bites” in the movie theater.

* Most shocking of all, the White House actually allowed her to be quoted by reporters outside the Taj Mahal: “When I was little, this was sort of the embodiment of the fairy-taled palace for me. . . .”

All are modest efforts by a usually ravenous media.

“They have never been so well-behaved,” remarks Chuck Conconi, editor at large at Washingtonian magazine.

*

It has gotten so that Chelsea can nearly come and go as she pleases, attending the ballet or theater with friends, a few Secret Service agents in tow, and remaining virtually unnoticed or a least undisturbed.

“I think she is having quite a good time in Washington,” says Lattimore, the first lady’s spokesman.

He was at the Kennedy Center last year when he saw Chelsea and some friends a few rows ahead. Someone approached her for an autograph. Lattimore instinctively prepared to intervene when, to his surprise, a patron at the end of her row did it for him, asking that Chelsea please be allowed to enjoy the ballet.

It’s no wonder that “Leave Chelsea Alone” T-shirts were a curbside item for a time.

Hillary Clinton says a driver’s license is on the horizon. The president will do the instructional honors. No car purchase is planned, but there is the first lady’s 1986 blue Oldsmobile Cutlass, still with Arkansas plates.

There has even been baby-sitting. Two nights of Chelsea-care, complete with Secret Service tag-alongs, were auctioned at a Sidwell Friends fund-raiser. “I think I said [at the time], ‘Those are going to be the safest kids in town,’ ” Lattimore says.

The intimacy of family life has benefited from what Hillary Clinton describes as “living above the store.” But she also is mindful that no amount of intimacy or shielding can offset the certainty of emancipation.

“These years of child rearing go by so fast,” she remarked wistfully to the New Yorker last month. “I mean, Chelsea’s going to be gone.”