Sienna's back.

Taking on a Hollywood blockbuster and a Broadway play, Sienna Miller gets ready to go from It girl to hit girl.

By Jonathan Van Meter. Photographed by Craig McDean.

If we were to begin this story in homage to the title of the book Sienna Miller is currently reading, our day together in New York City might be called Extremely Long and Incredibly Fun. But that would be misleading, because spending time with her feels less like a fanciful passage from a Jonathan Safran Foer novel and more like a madcap I Love Lucy episode.

Miller in person is tiny, blonde, blue-eyed, and, in black jeans with zippers at the ankle and a blue-and-white striped oxford shirt, just about as fetching as a girl can be. She woke up on the sheepish side of the bed today. Or at least that is how she describes her mood as we sit down for lunch at the Bowery Hotel and order pizza and white wine. She watched both versions of Grey Gardens the night before, and the heartbreaking grandiosity of the mother's and daughter's twin showbiz delusions has lingered. "Maybe that's what sent me into a tailspin," she says, laughing. "I'm in an Edie Beale head." But there is another reason she is not in full possession of her usual plucky confidence. Two nights ago, she sat through a screening of The Mysteries of Pittsburgh, a film she made in 2006 that opened and closed so fast this spring that if you weren't invited to the premiere you probably didn't see it.

It is as if she has just seen a ghost—her old self coming back to haunt her. Not only did she get asked on the red carpet about a gaffe she had thought she'd lived down (calling Pittsburgh "Shitsburgh" when she was making the film) but she also had to watch her own sex scenes in a theater filled with New York fashion people. "I don't think I feel comfortable getting naked now," she says. "I can see where I made the decision to make that film three years ago, but then you grow up and evolve and your tastes change. I was in this period where I was making movies back-to-back because I didn't want to be at home. Anything to not be in London. I was running away." Now 27, she's alluding to the defining moment of her young life, the Jude Law episode—"Nannygate," as she refers to it with genial resignation. She laughs and swats the subject away (for now) with a Lucille Ball-like crossed roll of the eyes. For many reasons, then, "seeing that film felt like a few steps back."

It does not take long, however, for Miller to snap out of her weird mood, partly because she does not enjoy being ponderous. But she is also genuinely excited because she is about to take two giant steps forward. On August 7, G.I. Joe: The Rise of Cobra opens: With a nearly $200 million budget, it is by far the biggest, most commercial film Miller has done. The same month, she begins rehearsals in New York for her Broadway debut in After Miss Julie, Patrick Marber's new drama based on August Strindberg's play, which will open at the American Airlines Theatre on October 22.

Starring in a huge summer action movie plus its antithesis, a clever English adaptation of a canonical nineteenth-century Scandinavian stage play, is a surprising one-two punch from an actress in need of an image change—and it is fraught with risk. But Miller is nothing if not brave. After all, she has long been battling the perception that she is, variously, a superficial party girl, a quirky fashion plate, an almost famous indie regular with no box-office clout, Jude Law's ex-girlfriend, or all of the above. "We have to be honest about it," says Miller of her reputation. "It's pretty bad. On the whole, you know, I've made some bad choices and done some stupid things." In other words: It is high time for a bold move. Or two.

Playing the Baroness, a cartoony villain in an action film, might seem at first like an ill-conceived strategy for a makeover. Guns and black leather? Rilly? But on closer inspection, it starts to look very clever indeed. G.I. Joe: The Rise of Cobra is based not on the G.I. Joe action figure of the sixties but on the wildly popular eighties Marvel Comics book series and television cartoon. The film is directed by Stephen Sommers, the man who unapologetically—indeed, enthusiastically—brings you larger-than-life popcorn fare like The Mummy and Van Helsing. What is less widely known about Sommers is that he is also the man who has persuaded English actresses like Rachel Weisz and Kate Beckinsale to work with him, women whose names do not spring to mind when one is casting action pictures. "I like very strong female characters, and somehow they all end up being British girls," he says. "So now it's Sienna Miller's turn."

The film has an odd ensemble cast: Jonathan Pryce, Dennis Quaid, Marlon Wayans, and Channing Tatum. But it is Tatum and Miller who have the most scenes together. "She is nut bags," says Tatum, underwear model turned actor, paying Miller a big compliment. "I love her like I can't even explain. She's one of those people who you can't help but be in a good mood when she's around. She just kind of intoxicates the room."

Having almost never been in any film bigger than very small, Miller found G.I. Joe, with its crew of 1,000 and near constant explosions, to be a huge challenge. "Initially I was terrified," she admits. "It was so out of my comfort zone. Everything gadget-wise that I had to use actually worked. I had these little guns, and if I fired them, lights came up and they made a sound. It was Disneyland for grown-ups."

When I ask if there was anything calculated in making such a choice, she plays it cool at first. "I'm not averse to being in big commercial films." But then she concedes, "I would be lying if I said it wasn't part of my consciousness to know this would probably, hopefully, be a successful film, and that that would be a smart thing to do. But I wouldn't have done it if I didn't think it was a good project, and it was different. I was kind of exhausted by my own choices, in a way; I was very happy to be in a film that was about having fun and not emotionally grueling for me or my family or friends, where I didn't put myself through some intense experience."

During casting, someone brought up Miller's name, and Sommers rented a bunch of DVDs. He quickly realized what so many people do when they finally take Sienna seriously: She's a talented and versatile actor. "For me, that role, it had to be a great actress," he says. "Because it could be wildly over-the-top—the outfit is—so I needed someone who could ground it and make us believe that it's real." He adds, "Steven Spielberg saw it a week ago, and one of the first things he said was, 'Who is that actress who plays the Baroness? She's great.' And I said, 'It's Sienna Miller,' and he said, 'That's Sienna Miller? Wow, she really pops.'"

After lunch we head upstairs to Miller's hotel suite so she can have a smoke. She opens the door and the room is a riot of tried-on clothes, balloons, flowers, candy wrappers, and today's New York Times spread all over the table. "It's insane, my room," she says, laughing. "I was just suddenly inundated with sweet gifts yesterday, but it looks like I'm having a Mad Hatter's tea party or my own private non-birthday." Her hotel room is like her life: complicated, messy, public, fun.

It's well known that Miller has, since Jude Law, been entangled in a series of somewhat baffling, ill-fated, and extremely well-documented relationships, all of which seem to have burned very brightly and then crashed to the ground. From Calvin Klein model turned indie-rock heartthrob Jamie Burke to oddball 40-ish Welsh actor Rhys Ifans, there is no discernible pattern, no type. Most notoriously, she took up with Balthazar Getty last summer, while he was still married to his wife, Rosetta, with whom he has four children. The paparazzi shot of Sienna and Balthazar on the balcony of a hotel room in Italy—Miller topless with a sailor's hat perched on her head at a tipsy angle—came close to self-sabotage. When I saw it I thought, Oh, dear.

Today, she is officially single and seems a bit repentant. When I ask about her love life and use the word dating she says, "I've actually never been taken on a date in my whole life. I have never had a one-night stand. I'm a real relationship person—contrary to public perception. I'm either in one or I'm not. I get kind of emotionally involved very quickly, and I'm not going to spend time with someone unless I love them. But it's not hard for me to fall in love."

I decide to ask about Jude Law—not to rehash the past but to see if, four years out, there is any fresh insight. "It's dangerous to bring this up," she says. "I talked about him in an interview not long ago, saying that I still love him, and he was like, 'Please stop talking about it.' " She laughs. "This was going to be the first interview where I was going to try to be guarded and detached, not give anything away, and actually I realize that it's irrelevant. You have to be yourself.…

"That was a very pivotal time in my life, and I'm happy saying that," she continues. "It's a private moment when you get your heart broken for the first time, and that was the absolute antithesis of private." She starts to laugh. "It couldn't have been more public! I had people on the street being like, ' 'Ang in there, loov!' and all you want to do is crawl into a cave and weep for a week." She pauses for a moment and then finds the bright side. "I think I discovered a whole new emotional depth that I didn't have access to before. When you have your heart broken for the first time, you gain depth, and that's why actors tend to get better with age, I think."

Not all that long ago Miller, with typical English bluster, was loudly declaring that therapy was for the birds. When I mention this, she tells me she has had a change of heart. Turns out a lady friend in New York gently suggested Miller seek therapy. "She took me out to lunch—funnily enough to a restaurant called Balthazar, which I thought was hilarious, but she never commented on the irony of that—and she said, 'You've been through hell, and you need to talk about it with someone.' I got to the point where I was doing things that I didn't necessarily think I was capable of as a person. And I wanted to be conscious of my actions. I think I was really naive and trusting and thinking that if you are true to yourself, that's enough, that's the best way to be. But actually, it's important to become more conscious."

She goes on: "Being the center of a lot of judgment and controversy while not feeling like a hurtful or controversial person in my essence, I'm trying to understand what it is that makes me that way and what it is that makes people feel that way about me."

After an hour break during which Miller, she later tells me, grabs a 20-minute nap, eats a cold slice, and takes a bath, she appears at my door in "a little frocklet" of her own design, by Twenty8Twelve, and a pair of major platforms that zipper up the back. We jump in a town car and head up to Times Square for a pretheater dinner.

As we inch up Sixth Avenue, I ask about her reputation as a trendsetter. "Teenage girls like certain things I wear—or certainly did when that whole boho thing happened. I was aware of it because I could see copies of the things I'd collected for years for five bucks. But I don't feel like a particularly fashionable person now; I don't feel like I have a huge influence. I don't mean to sound too self-deprecating, but I don't give too much thought to these things. I don't wake up feeling really fashionable." She laughs and then suddenly notices that there's a food stain on her dress. She stares at me for a second as if to say, See? "I definitely get it wrong a lot."

Moments later we are sitting on the third floor of Angus McIndoe, a popular theater-crowd hangout, with Jim Carnahan, a legendary New York character who is the casting director for the Roundabout Theatre Company, which is staging After Miss Julie. In the car, Miller described him as "really charismatic, wine-drinking, theater-loving—very up our street." I am not disappointed. He is loud, affable, and hilarious.

They haven't seen each other in about six weeks, since Miller, along with Carnahan, Marber, and the director, Mark Brokaw, auditioned actors in London to be her leading man. (Miller hated being on the other side of the auditioning process. "I wanted to be in Camp Actor," she says, "not Camp Decision.") Just a week ago, they cast Jonny Lee Miller, and everyone is thrilled, especially Sienna. "He's the nicest guy," she says. "When I found out, I texted him thinking that he knew, but he obviously hadn't heard yet. It was very unsubtle."

"So you two know each other from…?"

"Well, he's Jude's best friend," says Miller.

"Oh, God," says Carnahan.

Miller lets loose an exaggerated "evil" laugh—"Bwah-ha-ha-ha-HAAAA!"—and we all crack up. "Jude's probably like, Will this woman ever disappear?" Pause for effect. "Yooo-hoo!" Another big laugh. "Yeah, Jude, Jonny Lee Miller, and Ewan McGregor lived together. They all met when they were about ten years old at the National Youth Music Theatre and were best friends growing up."

Marber's version of the Strindberg classic (the first "naturalistic" tragedy) relocates the action from late-1800s Sweden to a country house outside London, the night of the British Labor Party's landslide election victory in 1945. Marber, who originally wrote and directed his version for the BBC in 1995, boiled it down to an 85-minute duel between John, a valet and chauffeur to a rich politician, and the pol's daughter, Miss Julie. In 2003, it was staged for the first time, at the Donmar Warehouse, a production that Miller saw twice with her then-boyfriend Law, who was at the time working on the film Closer, which was written by Marber ("Six Degrees of Jude Law," jokes Carnahan). "I think they're two people locked in a tragic relationship: due to circumstance, due to politics, due to class," says Marber about the characters. "It's a play about love and desire, and very, very crudely put, it's a play about a fuck. That's the whole point: two people who shouldn't but who do anyway, and the consequences of that." Because it is such a demanding role, Miss Julie is usually played by a woman in her mid-30s. "To see someone so young in this role is, I think, very exciting," says Marber.

It was Carnahan's idea to cast Miller. The Roundabout team, who are known for their inventive casting, had been talking about doing Strindberg's Miss Julie for years, and then one day the director, Brokaw, said he'd love to direct the Marber version. "And hand to God," says Carnahan, "not just because you're sitting here, I said, 'The perfect person for this part is Sienna Miller.' "

"I don't know whether to be flattered or horrified," says Miller. As she said to me earlier about the part, "She's kind of detestable in a lot of ways. That's something I struggle with, something I have to overcome. It's tricky subject matter. She's vulnerable, she's messed up, she's manipulative, she's promiscuous, she's damaged—all of the things I'm supposed to be, according to certain journalists, so I don't know whether I'm being really smart or really stupid."

She probably needn't worry. Although Miller has been typecast over the years, playing one damaged, needy, or screwed-up girl after another, and it is hard for some people to separate the actress from her roles, she is in fact, in many ways, the opposite of troubled. In person she's sunny, hilarious, game for anything, quick-witted (with an accent for every occasion), and extremely down-to-earth. As her friend Keira Knightley tells me, "I think she's unique because she's entirely herself. There isn't any pretext, she doesn't pretend to be anything that she isn't. And what she is is this amazing ball of energy. I love being around her because you catch that energy from her."

And in the end, it is her talent that landed her the role of Miss Julie. Carnahan tells a story about the night during the London run of As You Like It when her costar Helen McCrory collapsed from heat exhaustion during the matinee in an un-air-conditioned theater and Miller had to go on in the part of Rosalind—having never done it even in rehearsal. "I somehow got through it," says Miller, "but it was the most terrifying experience. I don't really remember much about it. I lost ten years of my life in one night."

"The producer Sonia Friedman was there," says Carnahan, "and she said you were amazing—unbelievable."

When Carnahan reiterates that Miller is perfect for Miss Julie, Miller sounds genuinely anguished. "But why?"

"I don't know!" he says. "Look. The woman has to be absolutely sexual and comfortable with being sexual. I didn't know you, I just knew your work as an actor; the films Interview and Factory Girl, they are both that."

"Yes?" says Miller.

"And we need someone believably beautiful and young and a good enough actor to pull this woman off. Patrick has taken the play and made it very English, and it felt like it needed to be a genuinely British actress. I mean, I really didn't even do a list. Usually when you start to do a play you do a list, and then you call the director and you go over it and you decide. But it really was, the perfect person is Sienna Miller. And it all worked out."

"Yaaaay!" she says and throws her arms around him.

"And here we are," he says, looking like the cat that ate the canary.

Miller pipes up, "Everyone keeps asking me what I'm doing next, and I keep singing, 'Broooooad-waaaay!' " Pause. "And then I realize: There is no music and I kill myself at the end!"

After dinner, we head over to the Barrymore Theatre to see Susan Sarandon in Exit the King. They met while they were making Alfie in 2003 and have stayed in touch. "She had my back," Miller says. "I was the new, young, naive I-can't-believe-I'm-in-a-film girl, and Susan was really good to me. I think she sees the traps I get myself into and can laugh at them from afar. She's proper cool."

The play is almost indescribably bizarre in the best possible way: intense, funny, scary, sad. At intermission, the lights come up, and we both sit there in stunned amazement. And then decide to head downstairs to the bar. Someone suddenly yells, "Sienna!" and a young, handsome guy named Tao comes over and they embrace. (Turns out she met him at Coachella last year. "He had this big, crazy painted bus, and we wound up getting on and traveling back to L.A. with him," she says.) How long are you here for? he asks her. I'm leaving tomorrow, she says. And then he utters a line that Miller takes special delight in: "Every time I see you, you're leaving tomorrow."

It is fascinating to see her in the company of a guy named Tao with a painted bus, because Miller herself is a bit of a throwback; she can very easily read as a kind of groovy hippie chick born in the wrong era. Directors obviously see this, too, what with Alfie and Edie Sedgwick. In fact, she will appear soon in Beeban Kidron's film Hippie Hippie Shake as...a hippie! Earlier in the day, I asked about her childhood in England. "It was always very loving and open. I described my dad as a hippie once, which he's not, but in his essence he's got a bohemian approach to life. It wasn't like we were in a camper van running around with flowers in our hair, naked. But you could express any emotion; if you felt something, you could say it; if you needed to talk, you could. I think that nonjudgmental way of being raised maybe contributed to my free-spiritedness."

While there's no danger of that free-spiritedness disappearing anytime soon, it's clear that Miller is growing and pushing herself in new ways. Along with the Hollywood blockbuster and Broadway gambits, the newfound reflectiveness about her love life and the therapy, she has also started to reach out to the world around her. She recently spent seven days in the Congo on behalf of International Medical Corps, a health and humanitarian organization that works in 25 countries. Her travel companion, Margaret Aguirre, says, "She was absolutely astounding, not only as a human being and an empathetic and compassionate and insightful person but completely a trouper every step of the way."

When the play ends, we head backstage to Sarandon's dressing room, and as soon as I see them together I get it: They are two peas in a pod. Sarandon has a kind of daffy sexuality (remember The Rocky Horror Picture Show?); she delights in being unconventional (not everyone can claim to have filmed a lesbian sex scene with Catherine Deneuve); she is a hippie at heart, dedicated to liberal causes; and she was a late bloomer. She did not become a household name until Bull Durham in 1988, nearly 20 years after she began working as an actor.

Within moments, they devolve into shop talk, two film actresses comparing notes about the horrors of doing a stage play. "When I did a play in London, oh, the anxiety and hell I put myself through!" says Miller. "I was a monster to be around."

"I have been weeping," says Sarandon. "I was so terrified. And then I was like, terrified is when your plane is about to crash into the World Trade Center. Terrified shouldn't be a play. It's all ego. Get over it. And I'd kind of chant myself down, and then I saw my name above the title and I lost it again. They make it into such a big deal. I mean, I made it into a big deal."

"You were amazing," says Miller. "It's absolutely obscure, but it's stunningly amazing. The anxiety doesn't come across at all."

"Geoffrey [Rush, Sarandon's costar] is so playful, and every time he screws up something he just starts laughing. That's been a real lesson. Exit the Ego."

They say their goodbyes, and we head out the stage door and onto the street. It's a strangely sultry evening for early April, and Miller seems to revel in the sight of all the theatergoers thronging around us. "It's really like an amazing dream," she says, her face lit up by the blazing wattage of the Great White Way. "As an actress, you can pack it all in after that. You've been on Broadway."

"Seriously Sienna" has been edited for; the complete story appears in the July 2009 issue of Vogue.

I just love her again! Great article, pics, and video from Vogue... I think I will definitely hit up her Broadway play.