NEW YORK — Cynthia Nixon has already starred on Broadway six times, worked in a dozen films, and appeared in numerous television programs. Yet, because she began acting so young, some people still think of her as a teenager, she says.
Ms. Nixon currently appears in the racy Broadway production ''Indiscretions,'' translated by Jeremy Sams from the 1938 Jean Cocteau play, ''Les Parents Terribles.'' She recently received her first Tony nomination, for her portrayal of a bohemian Paris bookbinder who finds herself having simultaneous affairs with a quirky inventor (Roger Rees) and his rambunctious son (Jude Law).
The daughter of a former actress, Nixon was introduced into the business by a family friend who was an agent. ''I started working when I was 12, in film and television,'' she says from her tiny third-floor dressing room at the Barrymore Theatre.
Two years later, she appeared in her first play, ''The Philadelphia Story,'' at Lincoln Center, and she has acted consistently ever since. She chose to continue her education and her career at the same time, believing that if she stopped working ''it would all dry up.''
Her high school years brought both opportunities and demands. ''People were very amenable,'' she says. ''They would rehearse me after school. When I was in the film 'Amadeus,' they flew me back and forth to Prague five times,'' to avoid missing too many classes.
The script for ''Indiscretions'' didn't win her over initially. ''I hated it when I read it,'' she says, explaining, ''But I feel you should always audition, because you can get such a sense of what the production is going to be like from the way the people are. And Sean [Mathias, the director] was just amazingly fun to audition for.''
Asked to describe the style of the piece, about a son-obsessed mother, her inattentive husband, her clear-headed sister, and the young woman who upends their lives, she collects her thoughts, then says: ''It keeps changing style. It starts off like a mystery, or a horror movie, almost. It goes through being a comedy of manners, a sex farce, a sweet romantic love story, and a Jacobian avengers tragedy. That's one of the challenges of it, one of the things that can lift you up.
''There are certain realistic touches that really enhance it, but whenever we have a choice between going for a heightened style or a naturalistic one, we always go for the heightened style, which is both thrilling and takes a lot of energy.''
Nixon is known for limitless energy. Early on, she was noticed not only for the quality of her work, but also for appearing in two Broadway shows at the same time. ''I was in rehearsal for Tom Stoppard's 'The Real Thing,' and Mike Nichols, the director, said, 'I have a script for you.' It was David Mamet's 'Hurlyburly'.... Both plays had the same director.''
They tried out the logistics a few times, since ''Hurlyburly'' was in the Barrymore on West 47th Street, and ''The Real Thing'' was at the Plymouth on West 45th Street.
For the following three months, she started at the Barrymore and shuttled between the theaters a few times during each two-hour performance, alternating between Mamet's ethereal street waif, Donna, and Stoppard's spoiled private-school girl, Debbie. ''That was during my first semester of college,'' she notes, ''and I had to leave early to get in my studies for finals.''
Nixon began taking formal acting classes only last year. ''I've always meant to, but for the first 10 years of my working life, I was in school,'' she explains. It wasn't until she signed the contract to perform in ''Angels in America'' (her last play before ''Indiscretions'') that she was able sign up to learn from renowned teacher Uta Hagen.
As a result of these classes, she says, she is better able to diagnose acting problems. ''Before, I'd think, 'It's just not working,' but now I have a much better diagnostic model. I've always been a very emotional actor. I would go right to the emotions of the character, rather than the circumstances.... Now I see that it's kind of a dead-end way to work.''
Nixon sees a troubling trend on the New York stage: ''There isn't room for moderate success anymore. They try to grab the biggest piece of the market they can, usually by making a really expensive production and loading it with stars and special effects.''
On a more hopeful note, she adds: ''I think the most heartening thing that has happened this season is Cherry Jones,'' a stunning young actress previously known only to theatre insiders, nominated for a Tony for her performance in ''The Heiress.''