"I think I've been around long enough for people to accept that I'm going to change in front of them," the 57-year-old two-time Oscar winner says in a recent phone conversation.
"At first, I was playing all those serious young women with long blond hair in 'The Deer Hunter,' 'Holocaust' and 'Kramer vs. Kramer.' If anything, I think people were happy to see me change," Streep adds.
Time magazine recently dubbed her "a legend but not a star," saying that her name brings prestige to a project but cannot justify big budgets or guarantee big box office.
"I've always thought of myself as a character actress, or a repertory actress," she says. "I don't even know if anyone understands what a repertory actor is anymore, so I better explain: It's when an actor plays a wide range of parts, ranging from royalty to waif."
In "The Devil Wears Prada," her Miranda Priestly character is definitely more royalty than waif. An off-with-their-heads monarch she is, declining to share elevators with lesser mortals and demanding that her coffee be served at an exact temperature.
"I've known a few Mirandas, but they've all been men," she says. "I'm not saying that women are automatically nicer than men. It may just be that not many women have been in true positions of power."
In the film, she makes life miserable for lowly Andy, a new assistant played by Anne Hathaway.
"I've never been in Andy's position," she says. "I've only had two jobs in my life, acting and waitressing. Both are relatively autonomous jobs. You receive direction, but you're on your own."
"The Devil Wears Prada" is based on a bestseller by Lauren Weisberger, who toiled as assistant to U.S. Vogue editor Anna Wintour. The novel's Miranda Priestly generally was accepted as a humorously unflattering portrait of Ms. Wintour, sometimes known in the fashion trade as "Nuclear Wintour."
"The film shouldn't be considered a documentary on Anna Wintour," Ms. Streep says. "In fact, I met her at a benefit screening of the movie, and she was very gracious and cordial. And she was wearing Prada."
Ms. Streep has been married to sculptor Don Gummer since 1978. They have four children, ranging in age from 15 to 27. Her oldest two children have acted under the names of Henry Gummer and Mamie Gummer.
"They're both wonderfully and uniquely talented. As long as acting nurtures them and doesn't kill their spirit, I'm thrilled for them to act. They grew up hearing me whine about the demands of the profession. After all, who can a mother whine to if not her own children? But they love acting."
When her children were growing up, they usually accompanied her on location. When she looks back on her films, she remembers them from a mother's perspective.
"When I was filming 'Out of Africa,' my daughter Grace was just 18 months old, and she rode on her brother's back wearing a beautiful antique dress from the movie. Whenever I think of the film, I think of the back of their beautiful golden heads walking off into the beautiful African sunset.
"When I look back on the filming of 'A Cry in the Dark,' I remember all of us at midnight in Australia, just listening to the sounds of the crickets and the other noises. We'd put our ears to the ground and listen."
THE DEVIL WEARS PRADA opens in Phils. theaters very soon this August from 20th Century Fox to be distributed by Warner Bros.