Cynthia Nixon’s BlackBerry is chirping and buzzing and a TV interview she did is playing in the lounge of Manhattan’s Laura Pels Theatre, but the actress calmly ignores it all. Her offstage serenity is a far cry from the character she just played in “Distracted,” the latest Roundabout Theatre Company production, in which she’s whipped into a constant frenzy by cell phones, TV shows and Internet news reports. But if Nixon is anything, she’s focused. Giving her on-screen self a once-over, all she says is, “I guess the lighting isn’t the best.”

This story first appeared in the March 10, 2009 issue of WWD. Subscribe Today.

This play, which centers on a mother’s struggle with her son’s possible attention deficit disorder and the medical and educational establishments’ drug-laden solutions, is merely the latest step in Nixon’s wide-ranging career, which began at age 11. The now 42-year-old’s résumé reads like a Who’s Who, featuring film, television and stage work with greats like Robert Altman, Mike Nichols, Wendy Wasserstein and Tony Kushner. Nixon has won a Tony, a Screen Actors Guild award, two Emmys and even a Grammy (for a spoken word album of Al Gore’s “An Inconvenient Truth”). So she’s hardly daunted by the fact that for eight performances a week, her character in “Distracted” barely leaves the stage or stops speaking. “You’ve got to pace yourself, but then you get into a groove,” she says, though she will admit to a bit of fatigue during the four-week rehearsal process. “I drank a lot of caffeinated tea.”

“Her capacity for work is boundless,” says director Mark Brokaw. “She is a real theater animal. She’s very collaborative.”

It’s a trait she developed growing up, when she used to prep performances with her mother, former actress Anne Knoll. “Maybe because I worked so much with my mom, I like to think of the director as my partner,” says Nixon, who bears no trace of a divalike ego. “The director can see — and you can’t. It may feel great and it may look terrible.”

Indeed, when she was filming the “Sex and the City” TV show, “I would watch every take,” says Nixon, who remembers that her agent lobbied hard to land her the role of Miranda Hobbes. “They kept telling her for months that they’d seen nobody better but they weren’t ready to cast me yet.”

Though some might view her work on “Sex and the City” as light fare for such a heavy-hitting actress, Nixon professes to be a big fan of the show. “I’m really proud of ‘Sex and the City.’ I think that sometimes, [people] feel like they can get on my good side by running it down,” she says. “And it’s like, ‘Wow — that’s my mother you are talking about.’ They say, ‘You are so much better than this,’ and it’s like, ‘Honey, there is nothing better than ‘Sex and the City.’

“So many people are famous for something that they really wish would go away, or that they are embarrassed of,” she continues. “I’m proud to be associated with it. This gave me so many opportunities.” On the other hand, she says, “It follows you around and sometimes you think, ‘Oh, I didn’t get that part because they only think I’m Miranda.’”

But that’s a small price to pay. The show gave Nixon, a die-hard Upper West Sider, the chance to stay East for shooting. “New York is where all my people are and I never wanted to leave,” says the Barnard grad. Another, less-expected boon was Miranda’s wardrobe, courtesy of Patricia Field’s costume department. “I have some great stuff,” says Nixon, who in real life occasionally works with stylists like Leslie Fremar and favors the minimalist look of Francisco Costa’s Calvin Klein designs for red-carpet outings. “I know better than to wear something that’s hard to wear,” says the actress. “Those awards shows are long days.”

It helps when Costa can do a personal fitting, as he did with Nixon for the London premiere of “Sex and the City” last summer. “Cynthia has an unassuming self-confidence, and I think that the way that she carries herself works well with my clothes — they look fresh on her, and that is very Calvin,” says Costa.

But as a woman who professes that she’s “not incredibly proactive” about her career, Nixon isn’t terribly interested in the trappings of celebrity, either. “If I only did theater, I would live much more cheaply than I do,” she says. The one place where she might welcome the spotlight to shine is on the New York City public school system, in which both her daughter and son are enrolled.

“We’ve got 1.1 million public school children [in New York City]. The more people with money and influence that spend their money and pay attention to the schools, the better they will be,” says Nixon, who is a spokeswoman for the Alliance for Quality Education (her partner, Christine Marinoni, was a director of the organization). “It’s very expensive to educate children. People don’t want their taxes to go for it because it takes such a big part, but it’s really important.”

For the most part, Nixon lives a quiet life, preferring to hang out with her family and see “a lot” of plays. This April she’ll be on-screen in the Alec Baldwin-produced indie movie “Lymelife,” about disaffected Connecticut couples in the late Seventies, and this fall, production will start on the “Sex and the City” film sequel. But until then, Nixon will most likely be found in Montauk, far from any distractions. “We just stay in and cook and look at the water,” she says. “And that’s about it.”