It is 3 o'clock on a wintry Tuesday afternoon and I am waiting for Jessica Lange in a steakhouse popular with locals in New York's Greenwich Village. Large leather booths, shiny brass railings and early-20th-century posters line the wood-panelled walls; it's like a less swanky, neighbourhood version of Sardi's, the infamous hangout for Broadway stars.

The lunch crowd has thinned out. She chose this spot, but I'm wondering if she'll show up. The interview was cancelled twice before. There's the sense that after a long, quality career, she's grown tired of talking about herself and her work. This time it's a film called Don't Come Knocking, in which she stars with her longtime companion, Sam Shepard, who wrote the script.

Suddenly she arrives, wearing a long, zipped black parka and dark glasses, probably to protect her from the glare of the public eye rather than what passes for sun in Manhattan in February. She blends in, like just another chic, slim New Yorker. Her windswept honey-coloured hair frames a look of determination. Unrecognised, she walks to the table, shakes my hand and says hello. She takes off her coat, sets the Louis Vuitton tote bag down and slides into the booth. From this point, it's all about the sunglasses. They have remained on, and every second that passes feels elongated by this fact. When, moments later, she removes them, it feels like an open, friendly gesture, especially since now she is smiling too.

"We've just gotten back from Mexico," she says. "We've been going there for about 10 years, south of the Yucatan. We have land down there and at some point we'll build a home. Now we stay at a local place. It's really great."

"We" means her and Shepard, the iconic American playwright and actor with whom she has lived since they met during the filming of Frances in 1982. Lange speaks with a soft, buttery voice that sounds vaguely southern and hillbillyish but doesn't mask a sophisticated, steely presence. She and Shepard have two children, Hannah, 20, and Walker, 18, and Lange has a daughter, Shura, 24, whose father is the Russian dancer Mikhail Baryshnikov.

Her personal life and professional life have certain parallels. She's been drawn to some of the most complicated and interesting men, while running a career that has been equally challenging and complex. Her life has been full. And age has not diminished her allure. Her face is luminous.

More conspicuous, though, are her hands. They are in constant motion. She slides one over the crest of her head and through her hair with unconscious ease. With an elbow propped on the table, she rubs her earlobe, her fingertips making circular motions around the modest ruby stud as she orders a cappuccino. Her long, slender fingers flutter, always moving. When the coffee arrives, she stirs the foam around and around with the tiny spoon, tapping it again and again on the edge of the cup. While talking, she often pulls the cuffs of her sleeves over the bases of her palms, seemingly a habitual and comforting move more than an indication of chill. She glides from one movement to the next, fingers now circling the rim of the wine glass filled with mineral water. Is it nerves? It's hard to tell.

Having never lived in Los Angeles, she bristles when asked if she has a home there. "Noooo..." she drawls, shaking her head, as if that would be tantamount to living inside an exhaust pipe.

Lange has always seemed like a reluctant movie star. She is private, her life hints at extreme highs and lows, but they're revealed only through her work. Later she'll tell me that she was never driven to perform, never driven to be the centre of attention, and it's believable. Fame happened to her, it wasn't something she sought; she's far more at home on a farm than on a red carpet.

For a long time, home was a farm in Virginia where she and Shepard raised their children. She would choose her roles carefully, she says, so as not to be away for too long. Either that or she would take her children with her - on location, with home schooling. Family, she affirms, has always been the most important thing in her life.

And all those years she was outside LA, by choice, did she ever feel it hurt her career? "A little bit, because I was so far outside, either living on a farm in Virginia or a ranch in New Mexico. It's like any other business: the more you're seen, the more you're in people's consciousness, the more connections you make, so that if your friends are going to do a movie..." she trails off. She doesn't seem particularly regretful, like she's missed out on anything worth missing.

Lange didn't want to raise her children in Hollywood, fearing the exposure would warp their perspective. This speaks to her values.

"I wanted them to have a childhood that had nothing to do with what I do. I think it worked out. They came with me on movie sets or sat backstage at the theatre. I allowed them into that world, but they were never exposed to the politics of it." But when I suggest that perhaps they had an idealised version of what an actor's life was like, she disagrees. "No, it was very practical. This is what their mother did. We'd go to Scotland or France or New York, and they'd come to the sets. This is what I did and, when I was working, this is what their lives were like."

Home is in New York now. Even though she has a cabin in northern Minnesota, where she is from, she spends most of her time here because family is close, with one daughter in university nearby and the other married, living in Rhode Island. Her life when she's not filming revolves around her son, still in high school and living at home. She says she goes to the theatre, museums, but specifics are not revealed. "It's pretty simple.

I do everything New Yorkers do." Just then, a look of melancholy sweeps the diffidence away. "Next year will be the first year I don't have a child in school. I'm not looking forward to it. He's the last one living at home. It will be interesting, I suppose. I don't know."

She seems sad, but Lange is not someone who sits back and laments. Jack Nicholson once described her as a cross between a fawn and a Buick. While she appears momentarily fragile, there is an instinct that kicks in to displace the vulnerability with steely reserve.

Unlike many of the characters she has played, she does not lose it. Or let down her guard in interviews. "I've gotten pretty good at not losing it. You're much more volatile when you're young. I don't feel that insane volatility like I used to, and I'm glad about it. I think a lot of it's choice. Like stress. You either say yes or no to it."

She makes it sound simple, but I suspect this balance didn't happen overnight. She says spending time with Buddhist teachers has had a huge impact on her psychology. "I can't say I'm a Buddhist , but it's what I believe in." She recalls what an eye-opening experience it is when you see the ability to be in charge of thoughts and emotions, but when asked how she has changed most over the years, she doesn't know.

"I don't spend much time thinking about that kind of stuff, so when I'm asked questions like that, I come up short. I think the most transformative power in my life has been my children. And the death of family. These things bring things into perspective - what's important, what's not. Where energy should be placed."

This is interesting. But vague. Her answers open doors to other questions. "I've been working very hard to try to make the choice to be happy. I think that's a choice.

I mean, you can't be happy if you're grieving or there's a tragedy, but in your normal life, do you let inconsequential things make you unhappy? That's something I've been working on. I don't want to be unhappy or bitter or miserable."

Lange has had a quality career in which she has tackled a wide range of tricky roles, often ones that explore catastrophic misery. Her choices have been character-driven and her most memorable parts have been women on the edge. Lange has walked this line gracefully: the murderous, erotic Cora in The Postman Always Rings Twice; the tragic country singer Patsy Cline in Sweet Dreams; Carly, the passionate, unpredictable army wife in Blue Sky, for which she won her second Oscar in 1995 - her first was for her role opposite Dustin Hoffman in Tootsie, in 1982.

There is Blanche DuBois in Tennessee Williams's A Streetcar Named Desire - first on Broadway with Alec Baldwin, then twice more, including a West End run in 1997; the morphine addict Mary Tyrone in Eugene O'Neill's Long Day's Journey into Night, and the mesmerising but disturbed actress Frances Farmer. So what is it in her that has drawn her to playing such intense, tragic women? "I've always found it easier to play those parts," she says, looking deep into her cappuccino. "I just think the larger the character, the easier it is. More than anything, though, as an actor, they're just fun to play.

"When I did Frances, I really understood her rage and entrapment, because I think..." she stops talking and waits until the waitress, who is refilling the glass with water, leaves. "I think I have played characters that I have not connected to emotionally and my work has suffered for it. But there are characters who are quite mad, and I understand what's at the core of it."

So how does she immerse herself in madness and not take it home? "If you have a real life, it keeps it in perspective. You leave it behind when it's over and go back to your real life. But it takes its toll. Especially on stage.

You're experiencing that kind of pain every night. Your body, physiologically... you find the body reacting to what the mind and heart are experiencing."

She admits that with certain characters she has had a hard time pulling herself out of it. She became vulnerable and the investment was great. "When I finished Frances, and when I finished doing Streetcar on stage, it sounds weird, but it was almost like grieving the loss of that person. Someone that was now gone from your life. There is a sense of mourning for that character. The first time I felt grieving was with Blanche.

I felt it with Mary Tyrone, where I really missed her. It has to do with how much you love the character. You actually do love them." So is loving them loving that part of yourself? Suddenly, Lange looks slightly taken aback. "I don't know. I've never thought of it like that... It all has to be somewhere inside you. It is the human experience, after all."

Early on, Lange lived a bohemian fairy tale. She was born on April 20, 1949, in the small town of Cloquet, Minnesota, in the American heartland. She is of Finnish and Polish extraction and the third of four children. They moved often around the state. Her father, Al, had a big personality and Lange adored him. Maybe it was his dream that gave his daughter the need to live on the land and raise her family on a farm.

While on scholarship at Minneapolis University to study art, Lange met her first and only husband, the photographer Paco Grande.

A Spaniard in his twenties, they bolted from middle America to see the world. They moved first to New York and Lange became part of the underground scene, the 1960s hippie lifestyle - where the only agenda was to discover new things. She was exploring modern dance, theatre, photography, and at 20 she left for Paris to study mime. Still married to Grande, she travelled back and forth, but at 25 returned to New York for good. The acting, she says, was simply the next step. "The fact that it stuck kind of surprised me as much as anyone." She fell in love with it, calling it "the first thing I landed on that felt complete".

It was New York in the 1970s and a whole new world opened up. Her marriage had broken down, she was signed as a model, but her break into films came in 1976 when she was scooped up into the claw of Dino De Laurentiis's remake of King Kong. It was a mess. She was derided by critics and condemned to the purgatory of bimbohood. But not for long. She dug herself out three years later and the role reconfigured the public's perception. Bob Fosse, with whom she had an affair, cast her as the angel of death in his brilliant biographical memoir, All That Jazz. As Angelique, Lange was ethereal and otherworldly. She commanded the screen. Then, in 1981, as Cora in Postman, she secured her place as a seriously dynamic actress and, with Nicholson, made the remake a classic.

We've been here for an hour and a half and Lange checks her watch. She has to go. She reaches into her bag and applies some lip balm and tells me that when she leaves she is going to run an errand and then go back home. She laughs, saying she is working out many things in her life right now. "It's hard," she says. "Control is a false notion. I don't think we control anything. I think we discipline ourselves. The only thing you can determine is how you respond. It really is about transformation more than control." She says there wasn't a specific shift or moment that opened her eyes to this, that it was more of a natural progression. And so, over the course of this natural evolution, there must have been disappointments and surprises. "What has surprised you about yourself?" I ask. "I have no idea. I can't think of anything at the moment..."

I give it another moment - allowing the silence to penetrate - but it becomes clear she's waiting for the silence to pass, to be filled with the next question. Maybe digging deep inside herself, as she has done in every role she's taken, isn't what she's in the mood for any more.