"When I was younger, I used to watch the Miss America pageant. When it was over I'd go into the bathroom, hold up a bottle of Sea Breeze mouthwash , look into the mirror and say, 'I'd like to thank . . .' " Tami Tappan's voice erupts into a splendidly warm laugh.

She got her chance to give her thanks. At 16, Tappan was the winner of this year's Helen Hayes Award for outstanding supporting actress for her performance in John Guare's "Lydie Breeze" at the New Playwrights' Theatre.

"Never in my life did I expect to win the award," Tappan says. Her mother, Joanne Tappan, didn't expect it either. "The poor lady in front of me that night will probably be deaf for the rest of her life," she says.

"I don't think I deserved to win it," Tappan continues, bouncing slightly in her seat, while tucking strands of blond hair behind each ear. "I'm not saying that I didn't work hard. But for some of these people it's their whole life."

She jumps up to search through a drawer for the collages she has made of her clips and assorted quotes and pictures. She wheels around proudly with the sampling of photos and headlines.

"Some things make your heart beat a little faster. The drama is one of them," reads a portion of one of the collages.

The "drama" is quickly becoming Tappan's whole life, too. Typically, a day for the Laurel High School junior begins at 6 a.m. in order to make an 8 a.m. school bell. If she's lucky, she can sandwich a short nap between homework and dinner before heading off to the Harlequin Dinner Theatre, where she is currently playing Juan Peron's mistress in "Evita." She gets home about midnight.

So far discussions about boys have been low-key. "I had one boyfriend but it didn't work out because of my schedule. He was jealous of the time I was spending on my acting," says Tappan. But when a free night does come up, she likes going with a date to a concert. She saw Bruce Springsteen. She enjoys progressive rock, new wave and Top 40.

Tappan has come to accept the fact she's so busy that her free time is next to nil. "My social time is my work time, but I like it," she says.

"Why should a woman have to choose just one?" another headline asks.

For all that, Tappan confesses to times when she doesn't work at it hard enough. "Sometimes I feel like a vegetable," she moans, even though she has just finished reading William Inge's "Picnic," Beth Henley's "Crimes of the Heart" and David Mamet's "The Words." She also is eager to take acting classes with Joy Zinoman, artistic director of the Studio Theatre. She's already cast to appear in a Studio production of "Landscape of the Body," another John Guare drama, in January. The play will reunite Tappan with director Jim Nicola, who directed her in "Lydie Breeze."

Over dinner, mother and daughter plot the near future.

"What's on for tomorrow night?" her mother asks.

"No rehearsals," Tappan replies.

"Do you want to audition for that role you talked about?"

"I'd like to."

"Well." Pause. "We'll have to evaluate the time it's going to take versus the value of the role."

Tappan is still too young to drive at night, and the trip from Laurel to downtown Washington takes up to 45 minutes. She drew laughter on the night of the Helen Hayes Awards in May when she thanked her parents and her brother for driving her to rehearsal.

"It's not only for fun anymore," says Tappan. Now she's shooting for the stars.

"It's finally here."

Tami and Joanne Tappan recently returned from a visit to New York. "John Guare got us up there with the idea of showing us there weren't only cold, calculating people there. We had a wonderful time," Joanne Tappan says.

The highlight of the trip was a visit to the drama department at the Juilliard School. There they met Marion Seldes, Tony award winner and a Juilliard drama teacher. Anxious about the cost of tuition, Joanne Tappan asked about the availability of scholarships. "My dear! Everyone is on some sort of scholarship. No one can afford to go here," Seldes replied. Joanne Tappan adds, "And then I got the catalogue and I realized, 'Yep, she's right.' "

Admission to Juilliard is by audition. Tappan plans to try in March of her senior year.

"Are you posture perfect?" asks another collage.

Arching forward like a preening sparrow, Tappan apologizes for habitually tightening the Velcro fasteners on the back brace she wears 20 hours a day to help correct a curvature of the spine. She apologizes for wearing polka-dot socks that don't match a pink sleeveless knit sweater and blue jeans. "I just threw them on because it's cold," she says. She also apologizes for cracking her gum. "Is that driving you crazy? My chewing gum?" she asks, carefully cracking it again.

She is wearing two different earrings. "No, I don't do it to be like Madonna. First of all because I can't stand her . . . And second of all, well, she really is a sleaze. She seems like she has no talent."

For her role as Sandy in "Grease" at the Castle Theatre, Tappan had to portray a cigarette-smoking vamp in one scene. The stretch between Tappan and that character was plainly apparent to her father, Michael, who chuckled knowingly in the audience. Where did Tappan get material for the scene? "I pretended I was on a Madonna video."

"Most important supporting role."

Tappan is growing up quickly. She works with adults, and acts out adult material. Her performance in "Lydie Breeze" dealt with rape. One night in rehearsals, her mother says, "Her scene partner grabbed her, and both some cast members and I thought he got a little carried away. I put a stop to that."

"A typical stage mother. Very protective," one of Tappan's former directors says of her mother. But Tony Jaworski, artistic director of the Castle Theatre, says, "Mother and daughter have a wonderful, close relationship."

The two once appeared on stage together in "The Sound of Music." Tappan, in sixth grade at the time, played Brigitta. Her mother played sister Margaretta.

Tappan's request for some spending money is met with a straightforward "What for?" from her mother, who explains that she banks all of Tami's checks. "Someday she'll be grateful." For both of them, the biggest "someday" is a proper education. "The only promise I extracted from all this was that she will go to college," says Joanne Tappan. "The only question is when."

Tappan frequently calls her mother "You woman of the '80s, you." And in Tappan's room, a card tucked into the corner of the dresser mirror reads, "Break a leg you tuff chick. Love, from Stage Mom."